-This is tar.info, produced by makeinfo version 4.13 from tar.texi.
+This is tar.info, produced by makeinfo version 5.9.93 from tar.texi.
-This manual is for GNU `tar' (version 1.28, 22 July 2014), which
+This manual is for GNU 'tar' (version 1.29, 14 April 2016), which
creates and extracts files from archives.
- Copyright (C) 1992, 1994-1997, 1999-2001, 2003-2013 Free Software
+ Copyright (C) 1992, 1994-1997, 1999-2001, 2003-2016 Free Software
Foundation, Inc.
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with the Invariant Sections being "GNU General Public
- License", with the Front-Cover Texts being "A GNU Manual", and
- with the Back-Cover Texts as in (a) below. A copy of the license
- is included in the section entitled "GNU Free Documentation
- License".
-
- (a) The FSF's Back-Cover Text is: "You have the freedom to copy
- and modify this GNU manual."
+ License", with the Front-Cover Texts being "A GNU Manual", and with
+ the Back-Cover Texts as in (a) below. A copy of the license is
+ included in the section entitled "GNU Free Documentation License".
+ (a) The FSF's Back-Cover Text is: "You have the freedom to copy and
+ modify this GNU manual."
INFO-DIR-SECTION Archiving
START-INFO-DIR-ENTRY
* Tar: (tar). Making tape (or disk) archives.
INFO-DIR-SECTION Individual utilities
START-INFO-DIR-ENTRY
-* tar: (tar)tar invocation. Invoking GNU `tar'.
+* tar: (tar)tar invocation. Invoking GNU 'tar'.
END-INFO-DIR-ENTRY
+\1f
+File: tar.info, Node: one, Prev: recurse, Up: Choosing
+
+6.10 Crossing File System Boundaries
+====================================
+
+'tar' will normally automatically cross file system boundaries in order
+to archive files which are part of a directory tree. You can change
+this behavior by running 'tar' and specifying '--one-file-system'. This
+option only affects files that are archived because they are in a
+directory that is being archived; 'tar' will still archive files
+explicitly named on the command line or through '--files-from',
+regardless of where they reside.
+
+'--one-file-system'
+ Prevents 'tar' from crossing file system boundaries when archiving.
+ Use in conjunction with any write operation.
+
+ The '--one-file-system' option causes 'tar' to modify its normal
+behavior in archiving the contents of directories. If a file in a
+directory is not on the same file system as the directory itself, then
+'tar' will not archive that file. If the file is a directory itself,
+'tar' will not archive anything beneath it; in other words, 'tar' will
+not cross mount points.
+
+ This option is useful for making full or incremental archival backups
+of a file system. If this option is used in conjunction with
+'--verbose' ('-v'), files that are excluded are mentioned by name on the
+standard error.
+
+* Menu:
+
+* directory:: Changing Directory
+* absolute:: Absolute File Names
+
+\1f
+File: tar.info, Node: directory, Next: absolute, Up: one
+
+6.10.1 Changing the Working Directory
+-------------------------------------
+
+To change the working directory in the middle of a list of file names,
+either on the command line or in a file specified using '--files-from'
+('-T'), use '--directory' ('-C'). This will change the working
+directory to the specified directory after that point in the list.
+
+'--directory=DIRECTORY'
+'-C DIRECTORY'
+ Changes the working directory in the middle of a command line.
+
+ For example,
+
+ $ tar -c -f jams.tar grape prune -C food cherry
+
+will place the files 'grape' and 'prune' from the current directory into
+the archive 'jams.tar', followed by the file 'cherry' from the directory
+'food'. This option is especially useful when you have several widely
+separated files that you want to store in the same archive.
+
+ Note that the file 'cherry' is recorded in the archive under the
+precise name 'cherry', _not_ 'food/cherry'. Thus, the archive will
+contain three files that all appear to have come from the same
+directory; if the archive is extracted with plain 'tar --extract', all
+three files will be written in the current directory.
+
+ Contrast this with the command,
+
+ $ tar -c -f jams.tar grape prune -C food red/cherry
+
+which records the third file in the archive under the name 'red/cherry'
+so that, if the archive is extracted using 'tar --extract', the third
+file will be written in a subdirectory named 'red'.
+
+ You can use the '--directory' option to make the archive independent
+of the original name of the directory holding the files. The following
+command places the files '/etc/passwd', '/etc/hosts', and '/lib/libc.a'
+into the archive 'foo.tar':
+
+ $ tar -c -f foo.tar -C /etc passwd hosts -C /lib libc.a
+
+However, the names of the archive members will be exactly what they were
+on the command line: 'passwd', 'hosts', and 'libc.a'. They will not
+appear to be related by file name to the original directories where
+those files were located.
+
+ Note that '--directory' options are interpreted consecutively. If
+'--directory' specifies a relative file name, it is interpreted relative
+to the then current directory, which might not be the same as the
+original current working directory of 'tar', due to a previous
+'--directory' option.
+
+ When using '--files-from' (*note files::), you can put various 'tar'
+options (including '-C') in the file list. Notice, however, that in
+this case the option and its argument may not be separated by
+whitespace. If you use short option, its argument must either follow
+the option letter immediately, without any intervening whitespace, or
+occupy the next line. Otherwise, if you use long option, separate its
+argument by an equal sign.
+
+ For instance, the file list for the above example will be:
+
+ -C/etc
+ passwd
+ hosts
+ --directory=/lib
+ libc.a
+
+To use it, you would invoke 'tar' as follows:
+
+ $ tar -c -f foo.tar --files-from list
+
+ The interpretation of options in file lists is disabled by
+'--verbatim-files-from' and '--null' options.
+
+\1f
+File: tar.info, Node: absolute, Prev: directory, Up: one
+
+6.10.2 Absolute File Names
+--------------------------
+
+By default, GNU 'tar' drops a leading '/' on input or output, and
+complains about file names containing a '..' component. There is an
+option that turns off this behavior:
+
+'--absolute-names'
+'-P'
+ Do not strip leading slashes from file names, and permit file names
+ containing a '..' file name component.
+
+ When 'tar' extracts archive members from an archive, it strips any
+leading slashes ('/') from the member name. This causes absolute member
+names in the archive to be treated as relative file names. This allows
+you to have such members extracted wherever you want, instead of being
+restricted to extracting the member in the exact directory named in the
+archive. For example, if the archive member has the name '/etc/passwd',
+'tar' will extract it as if the name were really 'etc/passwd'.
+
+ File names containing '..' can cause problems when extracting, so
+'tar' normally warns you about such files when creating an archive, and
+rejects attempts to extracts such files.
+
+ Other 'tar' programs do not do this. As a result, if you create an
+archive whose member names start with a slash, they will be difficult
+for other people with a non-GNU 'tar' program to use. Therefore, GNU
+'tar' also strips leading slashes from member names when putting members
+into the archive. For example, if you ask 'tar' to add the file
+'/bin/ls' to an archive, it will do so, but the member name will be
+'bin/ls'(1).
+
+ Symbolic links containing '..' or leading '/' can also cause problems
+when extracting, so 'tar' normally extracts them last; it may create
+empty files as placeholders during extraction.
+
+ If you use the '--absolute-names' ('-P') option, 'tar' will do none
+of these transformations.
+
+ To archive or extract files relative to the root directory, specify
+the '--absolute-names' ('-P') option.
+
+ Normally, 'tar' acts on files relative to the working
+directory--ignoring superior directory names when archiving, and
+ignoring leading slashes when extracting.
+
+ When you specify '--absolute-names' ('-P'), 'tar' stores file names
+including all superior directory names, and preserves leading slashes.
+If you only invoked 'tar' from the root directory you would never need
+the '--absolute-names' option, but using this option may be more
+convenient than switching to root.
+
+'--absolute-names'
+ Preserves full file names (including superior directory names) when
+ archiving and extracting files.
+
+ 'tar' prints out a message about removing the '/' from file names.
+This message appears once per GNU 'tar' invocation. It represents
+something which ought to be told; ignoring what it means can cause very
+serious surprises, later.
+
+ Some people, nevertheless, do not want to see this message. Wanting
+to play really dangerously, one may of course redirect 'tar' standard
+error to the sink. For example, under 'sh':
+
+ $ tar -c -f archive.tar /home 2> /dev/null
+
+Another solution, both nicer and simpler, would be to change to the '/'
+directory first, and then avoid absolute notation. For example:
+
+ $ tar -c -f archive.tar -C / home
+
+ *Note Integrity::, for some of the security-related implications of
+using this option.
+
+ ---------- Footnotes ----------
+
+ (1) A side effect of this is that when '--create' is used with
+'--verbose' the resulting output is not, generally speaking, the same as
+the one you'd get running 'tar --list' command. This may be important
+if you use some scripts for comparing both outputs. *Note listing
+member and file names::, for the information on how to handle this case.
+
+\1f
+File: tar.info, Node: Date input formats, Next: Formats, Prev: Choosing, Up: Top
+
+7 Date input formats
+********************
+
+First, a quote:
+
+ Our units of temporal measurement, from seconds on up to months,
+ are so complicated, asymmetrical and disjunctive so as to make
+ coherent mental reckoning in time all but impossible. Indeed, had
+ some tyrannical god contrived to enslave our minds to time, to make
+ it all but impossible for us to escape subjection to sodden
+ routines and unpleasant surprises, he could hardly have done better
+ than handing down our present system. It is like a set of
+ trapezoidal building blocks, with no vertical or horizontal
+ surfaces, like a language in which the simplest thought demands
+ ornate constructions, useless particles and lengthy
+ circumlocutions. Unlike the more successful patterns of language
+ and science, which enable us to face experience boldly or at least
+ level-headedly, our system of temporal calculation silently and
+ persistently encourages our terror of time.
+
+ ... It is as though architects had to measure length in feet, width
+ in meters and height in ells; as though basic instruction manuals
+ demanded a knowledge of five different languages. It is no wonder
+ then that we often look into our own immediate past or future, last
+ Tuesday or a week from Sunday, with feelings of helpless confusion.
+ ...
+
+ --Robert Grudin, 'Time and the Art of Living'.
+
+ This section describes the textual date representations that GNU
+programs accept. These are the strings you, as a user, can supply as
+arguments to the various programs. The C interface (via the
+'parse_datetime' function) is not described here.
+
+* Menu:
+
+* General date syntax:: Common rules.
+* Calendar date items:: 19 Dec 1994.
+* Time of day items:: 9:20pm.
+* Time zone items:: EST, PDT, UTC, ...
+* Combined date and time of day items:: 1972-09-24T20:02:00,000000-0500.
+* Day of week items:: Monday and others.
+* Relative items in date strings:: next tuesday, 2 years ago.
+* Pure numbers in date strings:: 19931219, 1440.
+* Seconds since the Epoch:: @1078100502.
+* Specifying time zone rules:: TZ="America/New_York", TZ="UTC0".
+* Authors of parse_datetime:: Bellovin, Eggert, Salz, Berets, et al.
+
+\1f
+File: tar.info, Node: General date syntax, Next: Calendar date items, Up: Date input formats
+
+7.1 General date syntax
+=======================
+
+A "date" is a string, possibly empty, containing many items separated by
+whitespace. The whitespace may be omitted when no ambiguity arises.
+The empty string means the beginning of today (i.e., midnight). Order
+of the items is immaterial. A date string may contain many flavors of
+items:
+
+ * calendar date items
+ * time of day items
+ * time zone items
+ * combined date and time of day items
+ * day of the week items
+ * relative items
+ * pure numbers.
+
+We describe each of these item types in turn, below.
+
+ A few ordinal numbers may be written out in words in some contexts.
+This is most useful for specifying day of the week items or relative
+items (see below). Among the most commonly used ordinal numbers, the
+word 'last' stands for -1, 'this' stands for 0, and 'first' and 'next'
+both stand for 1. Because the word 'second' stands for the unit of time
+there is no way to write the ordinal number 2, but for convenience
+'third' stands for 3, 'fourth' for 4, 'fifth' for 5, 'sixth' for 6,
+'seventh' for 7, 'eighth' for 8, 'ninth' for 9, 'tenth' for 10,
+'eleventh' for 11 and 'twelfth' for 12.
+
+ When a month is written this way, it is still considered to be
+written numerically, instead of being "spelled in full"; this changes
+the allowed strings.
+
+ In the current implementation, only English is supported for words
+and abbreviations like 'AM', 'DST', 'EST', 'first', 'January', 'Sunday',
+'tomorrow', and 'year'.
+
+ The output of the 'date' command is not always acceptable as a date
+string, not only because of the language problem, but also because there
+is no standard meaning for time zone items like 'IST'. When using
+'date' to generate a date string intended to be parsed later, specify a
+date format that is independent of language and that does not use time
+zone items other than 'UTC' and 'Z'. Here are some ways to do this:
+
+ $ LC_ALL=C TZ=UTC0 date
+ Mon Mar 1 00:21:42 UTC 2004
+ $ TZ=UTC0 date +'%Y-%m-%d %H:%M:%SZ'
+ 2004-03-01 00:21:42Z
+ $ date --rfc-3339=ns # --rfc-3339 is a GNU extension.
+ 2004-02-29 16:21:42.692722128-08:00
+ $ date --rfc-2822 # a GNU extension
+ Sun, 29 Feb 2004 16:21:42 -0800
+ $ date +'%Y-%m-%d %H:%M:%S %z' # %z is a GNU extension.
+ 2004-02-29 16:21:42 -0800
+ $ date +'@%s.%N' # %s and %N are GNU extensions.
+ @1078100502.692722128
+
+ Alphabetic case is completely ignored in dates. Comments may be
+introduced between round parentheses, as long as included parentheses
+are properly nested. Hyphens not followed by a digit are currently
+ignored. Leading zeros on numbers are ignored.
+
+ Invalid dates like '2005-02-29' or times like '24:00' are rejected.
+In the typical case of a host that does not support leap seconds, a time
+like '23:59:60' is rejected even if it corresponds to a valid leap
+second.
+
+\1f
+File: tar.info, Node: Calendar date items, Next: Time of day items, Prev: General date syntax, Up: Date input formats
+
+7.2 Calendar date items
+=======================
+
+A "calendar date item" specifies a day of the year. It is specified
+differently, depending on whether the month is specified numerically or
+literally. All these strings specify the same calendar date:
+
+ 1972-09-24 # ISO 8601.
+ 72-9-24 # Assume 19xx for 69 through 99,
+ # 20xx for 00 through 68.
+ 72-09-24 # Leading zeros are ignored.
+ 9/24/72 # Common U.S. writing.
+ 24 September 1972
+ 24 Sept 72 # September has a special abbreviation.
+ 24 Sep 72 # Three-letter abbreviations always allowed.
+ Sep 24, 1972
+ 24-sep-72
+ 24sep72
+
+ The year can also be omitted. In this case, the last specified year
+is used, or the current year if none. For example:
+
+ 9/24
+ sep 24
+
+ Here are the rules.
+
+ For numeric months, the ISO 8601 format 'YEAR-MONTH-DAY' is allowed,
+where YEAR is any positive number, MONTH is a number between 01 and 12,
+and DAY is a number between 01 and 31. A leading zero must be present
+if a number is less than ten. If YEAR is 68 or smaller, then 2000 is
+added to it; otherwise, if YEAR is less than 100, then 1900 is added to
+it. The construct 'MONTH/DAY/YEAR', popular in the United States, is
+accepted. Also 'MONTH/DAY', omitting the year.
+
+ Literal months may be spelled out in full: 'January', 'February',
+'March', 'April', 'May', 'June', 'July', 'August', 'September',
+'October', 'November' or 'December'. Literal months may be abbreviated
+to their first three letters, possibly followed by an abbreviating dot.
+It is also permitted to write 'Sept' instead of 'September'.
+
+ When months are written literally, the calendar date may be given as
+any of the following:
+
+ DAY MONTH YEAR
+ DAY MONTH
+ MONTH DAY YEAR
+ DAY-MONTH-YEAR
+
+ Or, omitting the year:
+
+ MONTH DAY
+
\1f
File: tar.info, Node: Time of day items, Next: Time zone items, Prev: Calendar date items, Up: Date input formats
8:02pm
20:02-0500 # In EST (U.S. Eastern Standard Time).
- More generally, the time of day may be given as
-`HOUR:MINUTE:SECOND', where HOUR is a number between 0 and 23, MINUTE
-is a number between 0 and 59, and SECOND is a number between 0 and 59
-possibly followed by `.' or `,' and a fraction containing one or more
-digits. Alternatively, `:SECOND' can be omitted, in which case it is
-taken to be zero. On the rare hosts that support leap seconds, SECOND
-may be 60.
-
- If the time is followed by `am' or `pm' (or `a.m.' or `p.m.'), HOUR
-is restricted to run from 1 to 12, and `:MINUTE' may be omitted (taken
-to be zero). `am' indicates the first half of the day, `pm' indicates
+ More generally, the time of day may be given as 'HOUR:MINUTE:SECOND',
+where HOUR is a number between 0 and 23, MINUTE is a number between 0
+and 59, and SECOND is a number between 0 and 59 possibly followed by '.'
+or ',' and a fraction containing one or more digits. Alternatively,
+':SECOND' can be omitted, in which case it is taken to be zero. On the
+rare hosts that support leap seconds, SECOND may be 60.
+
+ If the time is followed by 'am' or 'pm' (or 'a.m.' or 'p.m.'), HOUR
+is restricted to run from 1 to 12, and ':MINUTE' may be omitted (taken
+to be zero). 'am' indicates the first half of the day, 'pm' indicates
the second half of the day. In this notation, 12 is the predecessor of
-1: midnight is `12am' while noon is `12pm'. (This is the zero-oriented
-interpretation of `12am' and `12pm', as opposed to the old tradition
-derived from Latin which uses `12m' for noon and `12pm' for midnight.)
+1: midnight is '12am' while noon is '12pm'. (This is the zero-oriented
+interpretation of '12am' and '12pm', as opposed to the old tradition
+derived from Latin which uses '12m' for noon and '12pm' for midnight.)
The time may alternatively be followed by a time zone correction,
-expressed as `SHHMM', where S is `+' or `-', HH is a number of zone
+expressed as 'SHHMM', where S is '+' or '-', HH is a number of zone
hours and MM is a number of zone minutes. The zone minutes term, MM,
may be omitted, in which case the one- or two-digit correction is
-interpreted as a number of hours. You can also separate HH from MM
-with a colon. When a time zone correction is given this way, it forces
-interpretation of the time relative to Coordinated Universal Time
-(UTC), overriding any previous specification for the time zone or the
-local time zone. For example, `+0530' and `+05:30' both stand for the
-time zone 5.5 hours ahead of UTC (e.g., India). This is the best way to
+interpreted as a number of hours. You can also separate HH from MM with
+a colon. When a time zone correction is given this way, it forces
+interpretation of the time relative to Coordinated Universal Time (UTC),
+overriding any previous specification for the time zone or the local
+time zone. For example, '+0530' and '+05:30' both stand for the time
+zone 5.5 hours ahead of UTC (e.g., India). This is the best way to
specify a time zone correction by fractional parts of an hour. The
maximum zone correction is 24 hours.
- Either `am'/`pm' or a time zone correction may be specified, but not
+ Either 'am'/'pm' or a time zone correction may be specified, but not
both.
\1f
===================
A "time zone item" specifies an international time zone, indicated by a
-small set of letters, e.g., `UTC' or `Z' for Coordinated Universal
-Time. Any included periods are ignored. By following a
-non-daylight-saving time zone by the string `DST' in a separate word
-(that is, separated by some white space), the corresponding daylight
-saving time zone may be specified. Alternatively, a
-non-daylight-saving time zone can be followed by a time zone
-correction, to add the two values. This is normally done only for
-`UTC'; for example, `UTC+05:30' is equivalent to `+05:30'.
-
- Time zone items other than `UTC' and `Z' are obsolescent and are not
-recommended, because they are ambiguous; for example, `EST' has a
-different meaning in Australia than in the United States. Instead,
-it's better to use unambiguous numeric time zone corrections like
-`-0500', as described in the previous section.
+small set of letters, e.g., 'UTC' or 'Z' for Coordinated Universal Time.
+Any included periods are ignored. By following a non-daylight-saving
+time zone by the string 'DST' in a separate word (that is, separated by
+some white space), the corresponding daylight saving time zone may be
+specified. Alternatively, a non-daylight-saving time zone can be
+followed by a time zone correction, to add the two values. This is
+normally done only for 'UTC'; for example, 'UTC+05:30' is equivalent to
+'+05:30'.
+
+ Time zone items other than 'UTC' and 'Z' are obsolescent and are not
+recommended, because they are ambiguous; for example, 'EST' has a
+different meaning in Australia than in the United States. Instead, it's
+better to use unambiguous numeric time zone corrections like '-0500', as
+described in the previous section.
If neither a time zone item nor a time zone correction is supplied,
time stamps are interpreted using the rules of the default time zone
=======================================
The ISO 8601 date and time of day extended format consists of an ISO
-8601 date, a `T' character separator, and an ISO 8601 time of day.
-This format is also recognized if the `T' is replaced by a space.
+8601 date, a 'T' character separator, and an ISO 8601 time of day. This
+format is also recognized if the 'T' is replaced by a space.
In this format, the time of day should use 24-hour notation.
Fractional seconds are allowed, with either comma or period preceding
7.6 Day of week items
=====================
-The explicit mention of a day of the week will forward the date (only
-if necessary) to reach that day of the week in the future.
+The explicit mention of a day of the week will forward the date (only if
+necessary) to reach that day of the week in the future.
- Days of the week may be spelled out in full: `Sunday', `Monday',
-`Tuesday', `Wednesday', `Thursday', `Friday' or `Saturday'. Days may
-be abbreviated to their first three letters, optionally followed by a
-period. The special abbreviations `Tues' for `Tuesday', `Wednes' for
-`Wednesday' and `Thur' or `Thurs' for `Thursday' are also allowed.
+ Days of the week may be spelled out in full: 'Sunday', 'Monday',
+'Tuesday', 'Wednesday', 'Thursday', 'Friday' or 'Saturday'. Days may be
+abbreviated to their first three letters, optionally followed by a
+period. The special abbreviations 'Tues' for 'Tuesday', 'Wednes' for
+'Wednesday' and 'Thur' or 'Thurs' for 'Thursday' are also allowed.
A number may precede a day of the week item to move forward
-supplementary weeks. It is best used in expression like `third
-monday'. In this context, `last DAY' or `next DAY' is also acceptable;
-they move one week before or after the day that DAY by itself would
-represent.
+supplementary weeks. It is best used in expression like 'third monday'.
+In this context, 'last DAY' or 'next DAY' is also acceptable; they move
+one week before or after the day that DAY by itself would represent.
A comma following a day of the week item is ignored.
3 years
2 days
- The unit of time displacement may be selected by the string `year'
-or `month' for moving by whole years or months. These are fuzzy units,
-as years and months are not all of equal duration. More precise units
-are `fortnight' which is worth 14 days, `week' worth 7 days, `day'
-worth 24 hours, `hour' worth 60 minutes, `minute' or `min' worth 60
-seconds, and `second' or `sec' worth one second. An `s' suffix on
-these units is accepted and ignored.
+ The unit of time displacement may be selected by the string 'year' or
+'month' for moving by whole years or months. These are fuzzy units, as
+years and months are not all of equal duration. More precise units are
+'fortnight' which is worth 14 days, 'week' worth 7 days, 'day' worth 24
+hours, 'hour' worth 60 minutes, 'minute' or 'min' worth 60 seconds, and
+'second' or 'sec' worth one second. An 's' suffix on these units is
+accepted and ignored.
The unit of time may be preceded by a multiplier, given as an
optionally signed number. Unsigned numbers are taken as positively
signed. No number at all implies 1 for a multiplier. Following a
-relative item by the string `ago' is equivalent to preceding the unit
-by a multiplier with value -1.
+relative item by the string 'ago' is equivalent to preceding the unit by
+a multiplier with value -1.
- The string `tomorrow' is worth one day in the future (equivalent to
-`day'), the string `yesterday' is worth one day in the past (equivalent
-to `day ago').
+ The string 'tomorrow' is worth one day in the future (equivalent to
+'day'), the string 'yesterday' is worth one day in the past (equivalent
+to 'day ago').
- The strings `now' or `today' are relative items corresponding to
+ The strings 'now' or 'today' are relative items corresponding to
zero-valued time displacement, these strings come from the fact a
zero-valued time displacement represents the current time when not
otherwise changed by previous items. They may be used to stress other
-items, like in `12:00 today'. The string `this' also has the meaning
-of a zero-valued time displacement, but is preferred in date strings
-like `this thursday'.
+items, like in '12:00 today'. The string 'this' also has the meaning of
+a zero-valued time displacement, but is preferred in date strings like
+'this thursday'.
When a relative item causes the resulting date to cross a boundary
where the clocks were adjusted, typically for daylight saving time, the
resulting date and time are adjusted accordingly.
The fuzz in units can cause problems with relative items. For
-example, `2003-07-31 -1 month' might evaluate to 2003-07-01, because
+example, '2003-07-31 -1 month' might evaluate to 2003-07-01, because
2003-06-31 is an invalid date. To determine the previous month more
reliably, you can ask for the month before the 15th of the current
month. For example:
Last month was June!
Also, take care when manipulating dates around clock changes such as
-daylight saving leaps. In a few cases these have added or subtracted
-as much as 24 hours from the clock, so it is often wise to adopt
-universal time by setting the `TZ' environment variable to `UTC0'
-before embarking on calendrical calculations.
+daylight saving leaps. In a few cases these have added or subtracted as
+much as 24 hours from the clock, so it is often wise to adopt universal
+time by setting the 'TZ' environment variable to 'UTC0' before embarking
+on calendrical calculations.
\1f
File: tar.info, Node: Pure numbers in date strings, Next: Seconds since the Epoch, Prev: Relative items in date strings, Up: Date input formats
7.9 Seconds since the Epoch
===========================
-If you precede a number with `@', it represents an internal time stamp
-as a count of seconds. The number can contain an internal decimal
-point (either `.' or `,'); any excess precision not supported by the
-internal representation is truncated toward minus infinity. Such a
-number cannot be combined with any other date item, as it specifies a
-complete time stamp.
+If you precede a number with '@', it represents an internal time stamp
+as a count of seconds. The number can contain an internal decimal point
+(either '.' or ','); any excess precision not supported by the internal
+representation is truncated toward minus infinity. Such a number cannot
+be combined with any other date item, as it specifies a complete time
+stamp.
Internally, computer times are represented as a count of seconds
-since an epoch--a well-defined point of time. On GNU and POSIX
-systems, the epoch is 1970-01-01 00:00:00 UTC, so `@0' represents this
-time, `@1' represents 1970-01-01 00:00:01 UTC, and so forth. GNU and
-most other POSIX-compliant systems support such times as an extension
-to POSIX, using negative counts, so that `@-1' represents 1969-12-31
-23:59:59 UTC.
+since an epoch--a well-defined point of time. On GNU and POSIX systems,
+the epoch is 1970-01-01 00:00:00 UTC, so '@0' represents this time, '@1'
+represents 1970-01-01 00:00:01 UTC, and so forth. GNU and most other
+POSIX-compliant systems support such times as an extension to POSIX,
+using negative counts, so that '@-1' represents 1969-12-31 23:59:59 UTC.
Traditional Unix systems count seconds with 32-bit two's-complement
integers and can represent times from 1901-12-13 20:45:52 through
seconds with nanosecond subcounts, and can represent all the times in
the known lifetime of the universe to a resolution of 1 nanosecond.
- On most hosts, these counts ignore the presence of leap seconds.
-For example, on most hosts `@915148799' represents 1998-12-31 23:59:59
-UTC, `@915148800' represents 1999-01-01 00:00:00 UTC, and there is no
-way to represent the intervening leap second 1998-12-31 23:59:60 UTC.
+ On most hosts, these counts ignore the presence of leap seconds. For
+example, on most hosts '@915148799' represents 1998-12-31 23:59:59 UTC,
+'@915148800' represents 1999-01-01 00:00:00 UTC, and there is no way to
+represent the intervening leap second 1998-12-31 23:59:60 UTC.
\1f
File: tar.info, Node: Specifying time zone rules, Next: Authors of parse_datetime, Prev: Seconds since the Epoch, Up: Date input formats
===============================
Normally, dates are interpreted using the rules of the current time
-zone, which in turn are specified by the `TZ' environment variable, or
-by a system default if `TZ' is not set. To specify a different set of
-default time zone rules that apply just to one date, start the date
-with a string of the form `TZ="RULE"'. The two quote characters (`"')
-must be present in the date, and any quotes or backslashes within RULE
-must be escaped by a backslash.
-
- For example, with the GNU `date' command you can answer the question
+zone, which in turn are specified by the 'TZ' environment variable, or
+by a system default if 'TZ' is not set. To specify a different set of
+default time zone rules that apply just to one date, start the date with
+a string of the form 'TZ="RULE"'. The two quote characters ('"') must
+be present in the date, and any quotes or backslashes within RULE must
+be escaped by a backslash.
+
+ For example, with the GNU 'date' command you can answer the question
"What time is it in New York when a Paris clock shows 6:30am on October
-31, 2004?" by using a date beginning with `TZ="Europe/Paris"' as shown
+31, 2004?" by using a date beginning with 'TZ="Europe/Paris"' as shown
in the following shell transcript:
$ export TZ="America/New_York"
$ date --date='TZ="Europe/Paris" 2004-10-31 06:30'
Sun Oct 31 01:30:00 EDT 2004
- In this example, the `--date' operand begins with its own `TZ'
+ In this example, the '--date' operand begins with its own 'TZ'
setting, so the rest of that operand is processed according to
-`Europe/Paris' rules, treating the string `2004-10-31 06:30' as if it
-were in Paris. However, since the output of the `date' command is
+'Europe/Paris' rules, treating the string '2004-10-31 06:30' as if it
+were in Paris. However, since the output of the 'date' command is
processed according to the overall time zone rules, it uses New York
-time. (Paris was normally six hours ahead of New York in 2004, but
-this example refers to a brief Halloween period when the gap was five
-hours.)
+time. (Paris was normally six hours ahead of New York in 2004, but this
+example refers to a brief Halloween period when the gap was five hours.)
- A `TZ' value is a rule that typically names a location in the `tz'
+ A 'TZ' value is a rule that typically names a location in the 'tz'
database (http://www.twinsun.com/tz/tz-link.htm). A recent catalog of
location names appears in the TWiki Date and Time Gateway
(http://twiki.org/cgi-bin/xtra/tzdate). A few non-GNU hosts require a
-colon before a location name in a `TZ' setting, e.g.,
-`TZ=":America/New_York"'.
+colon before a location name in a 'TZ' setting, e.g.,
+'TZ=":America/New_York"'.
- The `tz' database includes a wide variety of locations ranging from
-`Arctic/Longyearbyen' to `Antarctica/South_Pole', but if you are at sea
+ The 'tz' database includes a wide variety of locations ranging from
+'Arctic/Longyearbyen' to 'Antarctica/South_Pole', but if you are at sea
and have your own private time zone, or if you are using a non-GNU host
-that does not support the `tz' database, you may need to use a POSIX
-rule instead. Simple POSIX rules like `UTC0' specify a time zone
+that does not support the 'tz' database, you may need to use a POSIX
+rule instead. Simple POSIX rules like 'UTC0' specify a time zone
without daylight saving time; other rules can specify simple daylight
-saving regimes. *Note Specifying the Time Zone with `TZ': (libc)TZ
+saving regimes. *Note Specifying the Time Zone with 'TZ': (libc)TZ
Variable.
\1f
File: tar.info, Node: Authors of parse_datetime, Prev: Specifying time zone rules, Up: Date input formats
-7.11 Authors of `parse_datetime'
+7.11 Authors of 'parse_datetime'
================================
-`parse_datetime' started life as `getdate', as originally implemented
-by Steven M. Bellovin (<smb@research.att.com>) while at the University
-of North Carolina at Chapel Hill. The code was later tweaked by a
-couple of people on Usenet, then completely overhauled by Rich $alz
+'parse_datetime' started life as 'getdate', as originally implemented by
+Steven M. Bellovin (<smb@research.att.com>) while at the University of
+North Carolina at Chapel Hill. The code was later tweaked by a couple
+of people on Usenet, then completely overhauled by Rich $alz
(<rsalz@bbn.com>) and Jim Berets (<jberets@bbn.com>) in August, 1990.
Various revisions for the GNU system were made by David MacKenzie, Jim
-Meyering, Paul Eggert and others, including renaming it to `get_date' to
-avoid a conflict with the alternative Posix function `getdate', and a
-later rename to `parse_datetime'. The Posix function `getdate' can
-parse more locale-specific dates using `strptime', but relies on an
+Meyering, Paul Eggert and others, including renaming it to 'get_date' to
+avoid a conflict with the alternative Posix function 'getdate', and a
+later rename to 'parse_datetime'. The Posix function 'getdate' can
+parse more locale-specific dates using 'strptime', but relies on an
environment variable and external file, and lacks the thread-safety of
-`parse_datetime'.
+'parse_datetime'.
This chapter was originally produced by Franc,ois Pinard
-(<pinard@iro.umontreal.ca>) from the `parse_datetime.y' source code,
-and then edited by K. Berry (<kb@cs.umb.edu>).
+(<pinard@iro.umontreal.ca>) from the 'parse_datetime.y' source code, and
+then edited by K. Berry (<kb@cs.umb.edu>).
\1f
File: tar.info, Node: Formats, Next: Media, Prev: Date input formats, Up: Top
formats. The most frequently used formats are (in alphabetical order):
gnu
- Format used by GNU `tar' versions up to 1.13.25. This format
- derived from an early POSIX standard, adding some improvements
- such as sparse file handling and incremental archives.
- Unfortunately these features were implemented in a way
- incompatible with other archive formats.
+ Format used by GNU 'tar' versions up to 1.13.25. This format
+ derived from an early POSIX standard, adding some improvements such
+ as sparse file handling and incremental archives. Unfortunately
+ these features were implemented in a way incompatible with other
+ archive formats.
- Archives in `gnu' format are able to hold file names of unlimited
+ Archives in 'gnu' format are able to hold file names of unlimited
length.
oldgnu
- Format used by GNU `tar' of versions prior to 1.12.
+ Format used by GNU 'tar' of versions prior to 1.12.
v7
Archive format, compatible with the V7 implementation of tar. This
are:
1. The maximum length of a file name is limited to 99 characters.
-
2. The maximum length of a symbolic link is limited to 99
characters.
-
3. It is impossible to store special files (block and character
devices, fifos etc.)
-
4. Maximum value of user or group ID is limited to 2097151
(7777777 octal)
-
5. V7 archives do not contain symbolic ownership information
(user and group name of the file owner).
This format has traditionally been used by Automake when producing
Makefiles. This practice will change in the future, in the
meantime, however this means that projects containing file names
- more than 99 characters long will not be able to use GNU `tar'
- 1.28 and Automake prior to 1.9.
+ more than 99 characters long will not be able to use GNU 'tar' 1.29
+ and Automake prior to 1.9.
ustar
Archive format defined by POSIX.1-1988 specification. It stores
directory separator in two parts, first of them being at most
155 bytes long. So, in most cases the maximum file name
length will be shorter than 256 characters.
-
2. The maximum length of a symbolic link name is limited to 100
characters.
-
3. Maximum size of a file the archive is able to accommodate is
8GB
-
4. Maximum value of UID/GID is 2097151.
-
5. Maximum number of bits in device major and minor numbers is
21.
star
- Format used by Jo"rg Schilling `star' implementation. GNU `tar'
- is able to read `star' archives but currently does not produce
- them.
+ Format used by Jo"rg Schilling 'star' implementation. GNU 'tar' is
+ able to read 'star' archives but currently does not produce them.
posix
Archive format defined by POSIX.1-2001 specification. This is the
restrictions on file sizes or file name lengths. This format is
quite recent, so not all tar implementations are able to handle it
properly. However, this format is designed in such a way that any
- tar implementation able to read `ustar' archives will be able to
- read most `posix' archives as well, with the only exception that
+ tar implementation able to read 'ustar' archives will be able to
+ read most 'posix' archives as well, with the only exception that
any additional information (such as long file names etc.) will in
such case be extracted as plain text files along with the files it
refers to.
This archive format will be the default format for future versions
- of GNU `tar'.
-
+ of GNU 'tar'.
The following table summarizes the limitations of each of these
formats:
Format UID File Size File Name Devn
---------------------------------------------------------------------
+--------------------------------------------------------------------
gnu 1.8e19 Unlimited Unlimited 63
oldgnu 1.8e19 Unlimited Unlimited 63
v7 2097151 8GB 99 n/a
ustar 2097151 8GB 256 21
posix Unlimited Unlimited Unlimited Unlimited
- The default format for GNU `tar' is defined at compilation time.
-You may check it by running `tar --help', and examining the last lines
-of its output. Usually, GNU `tar' is configured to create archives in
-`gnu' format, however, future version will switch to `posix'.
+ The default format for GNU 'tar' is defined at compilation time. You
+may check it by running 'tar --help', and examining the last lines of
+its output. Usually, GNU 'tar' is configured to create archives in
+'gnu' format, however, future version will switch to 'posix'.
* Menu:
* Compression:: Using Less Space through Compression
* Attributes:: Handling File Attributes
-* Portability:: Making `tar' Archives More Portable
-* cpio:: Comparison of `tar' and `cpio'
+* Portability:: Making 'tar' Archives More Portable
+* cpio:: Comparison of 'tar' and 'cpio'
\1f
File: tar.info, Node: Compression, Next: Attributes, Up: Formats
8.1.1 Creating and Reading Compressed Archives
----------------------------------------------
-GNU `tar' is able to create and read compressed archives. It supports
-a wide variety of compression programs, namely: `gzip', `bzip2',
-`lzip', `lzma', `lzop', `xz' and traditional `compress'. The latter is
+GNU 'tar' is able to create and read compressed archives. It supports a
+wide variety of compression programs, namely: 'gzip', 'bzip2', 'lzip',
+'lzma', 'lzop', 'xz' and traditional 'compress'. The latter is
supported mostly for backward compatibility, and we recommend against
-using it, because it is by far less effective than the other
-compression programs(1).
+using it, because it is by far less effective than the other compression
+programs(1).
Creating a compressed archive is simple: you just specify a
"compression option" along with the usual archive creation commands.
-The compression option is `-z' (`--gzip') to create a `gzip' compressed
-archive, `-j' (`--bzip2') to create a `bzip2' compressed archive,
-`--lzip' to create an lzip compressed archive, `-J' (`--xz') to create
-an XZ archive, `--lzma' to create an LZMA compressed archive, `--lzop'
-to create an LSOP archive, and `-Z' (`--compress') to use `compress'
+The compression option is '-z' ('--gzip') to create a 'gzip' compressed
+archive, '-j' ('--bzip2') to create a 'bzip2' compressed archive,
+'--lzip' to create an lzip compressed archive, '-J' ('--xz') to create
+an XZ archive, '--lzma' to create an LZMA compressed archive, '--lzop'
+to create an LSOP archive, and '-Z' ('--compress') to use 'compress'
program. For example:
$ tar czf archive.tar.gz .
- You can also let GNU `tar' select the compression program based on
-the suffix of the archive file name. This is done using
-`--auto-compress' (`-a') command line option. For example, the
-following invocation will use `bzip2' for compression:
+ You can also let GNU 'tar' select the compression program based on
+the suffix of the archive file name. This is done using
+'--auto-compress' ('-a') command line option. For example, the
+following invocation will use 'bzip2' for compression:
$ tar caf archive.tar.bz2 .
-whereas the following one will use `lzma':
+whereas the following one will use 'lzma':
$ tar caf archive.tar.lzma .
- For a complete list of file name suffixes recognized by GNU `tar',
+ For a complete list of file name suffixes recognized by GNU 'tar',
see *note auto-compress::.
Reading compressed archive is even simpler: you don't need to specify
-any additional options as GNU `tar' recognizes its format
-automatically. Thus, the following commands will list and extract the
-archive created in previous example:
+any additional options as GNU 'tar' recognizes its format automatically.
+Thus, the following commands will list and extract the archive created
+in previous example:
# List the compressed archive
$ tar tf archive.tar.gz
The format recognition algorithm is based on "signatures", a special
byte sequences in the beginning of file, that are specific for certain
-compression formats. If this approach fails, `tar' falls back to using
+compression formats. If this approach fails, 'tar' falls back to using
archive name suffix to determine its format (*note auto-compress::, for
a list of recognized suffixes).
Some compression programs are able to handle different compression
-formats. GNU `tar' uses this, if the principal decompressor for the
-given format is not available. For example, if `compress' is not
-installed, `tar' will try to use `gzip'. As of version 1.28 the
+formats. GNU 'tar' uses this, if the principal decompressor for the
+given format is not available. For example, if 'compress' is not
+installed, 'tar' will try to use 'gzip'. As of version 1.29 the
following alternatives are tried(2):
Format Main decompressor Alternatives
----------------------------------------------------------------------
+---------------------------------------------------------------------
compress compress gzip
lzma lzma xz
bzip2 bzip2 lbzip2
The only case when you have to specify a decompression option while
reading the archive is when reading from a pipe or from a tape drive
-that does not support random access. However, in this case GNU `tar'
+that does not support random access. However, in this case GNU 'tar'
will indicate which option you should use. For example:
$ cat archive.tar.gz | tar tf -
tar: Error is not recoverable: exiting now
If you see such diagnostics, just add the suggested option to the
-invocation of GNU `tar':
+invocation of GNU 'tar':
$ cat archive.tar.gz | tar tzf -
Notice also, that there are several restrictions on operations on
compressed archives. First of all, compressed archives cannot be
-modified, i.e., you cannot update (`--update', alias `-u') them or
-delete (`--delete') members from them or add (`--append', alias `-r')
-members to them. Likewise, you cannot append another `tar' archive to
-a compressed archive using `--concatenate' (`-A'). Secondly,
-multi-volume archives cannot be compressed.
+modified, i.e., you cannot update ('--update', alias '-u') them or
+delete ('--delete') members from them or add ('--append', alias '-r')
+members to them. Likewise, you cannot append another 'tar' archive to a
+compressed archive using '--concatenate' ('-A'). Secondly, multi-volume
+archives cannot be compressed.
The following options allow to select a particular compressor
program:
-`-z'
-`--gzip'
-`--ungzip'
- Filter the archive through `gzip'.
+'-z'
+'--gzip'
+'--ungzip'
+ Filter the archive through 'gzip'.
-`-J'
-`--xz'
- Filter the archive through `xz'.
+'-J'
+'--xz'
+ Filter the archive through 'xz'.
-`-j'
-`--bzip2'
- Filter the archive through `bzip2'.
+'-j'
+'--bzip2'
+ Filter the archive through 'bzip2'.
-`--lzip'
- Filter the archive through `lzip'.
+'--lzip'
+ Filter the archive through 'lzip'.
-`--lzma'
- Filter the archive through `lzma'.
+'--lzma'
+ Filter the archive through 'lzma'.
-`--lzop'
- Filter the archive through `lzop'.
+'--lzop'
+ Filter the archive through 'lzop'.
-`-Z'
-`--compress'
-`--uncompress'
- Filter the archive through `compress'.
+'-Z'
+'--compress'
+'--uncompress'
+ Filter the archive through 'compress'.
- When any of these options is given, GNU `tar' searches the compressor
+ When any of these options is given, GNU 'tar' searches the compressor
binary in the current path and invokes it. The name of the compressor
program is specified at compilation time using a corresponding
-`--with-COMPNAME' option to `configure', e.g. `--with-bzip2' to select
-a specific `bzip2' binary. *Note lbzip2::, for a detailed discussion.
+'--with-COMPNAME' option to 'configure', e.g. '--with-bzip2' to select
+a specific 'bzip2' binary. *Note lbzip2::, for a detailed discussion.
- The output produced by `tar --help' shows the actual compressor
-names along with each of these options.
+ The output produced by 'tar --help' shows the actual compressor names
+along with each of these options.
You can use any of these options on physical devices (tape drives,
etc.) and remote files as well as on normal files; data to or from such
-devices or remote files is reblocked by another copy of the `tar'
+devices or remote files is reblocked by another copy of the 'tar'
program to enforce the specified (or default) record size. The default
-compression parameters are used. Most compression programs let you
-override these by setting a program-specific environment variable. For
-example, with `gzip' you can set `GZIP':
-
- $ GZIP='-9 -n' tar czf archive.tar.gz subdir
- Another way would be to use the `-I' option instead (see below),
-e.g.:
+compression parameters are used. You can override them by using the
+'-I' option (see below), e.g.:
$ tar -cf archive.tar.gz -I 'gzip -9 -n' subdir
-Finally, the third, traditional, way to do this is to use a pipe:
+A more traditional way to do this is to use a pipe:
$ tar cf - subdir | gzip -9 -n > archive.tar.gz
Other compression options provide better control over creating
compressed archives. These are:
-`--auto-compress'
-`-a'
+'--auto-compress'
+'-a'
Select a compression program to use by the archive file name
suffix. The following suffixes are recognized:
- Suffix Compression program
- --------------------------------------------------------------
- `.gz' `gzip'
- `.tgz' `gzip'
- `.taz' `gzip'
- `.Z' `compress'
- `.taZ' `compress'
- `.bz2' `bzip2'
- `.tz2' `bzip2'
- `.tbz2' `bzip2'
- `.tbz' `bzip2'
- `.lz' `lzip'
- `.lzma' `lzma'
- `.tlz' `lzma'
- `.lzo' `lzop'
- `.xz' `xz'
-
-`--use-compress-program=COMMAND'
-`-I=COMMAND'
+ Suffix Compression program
+ -------------------------------------------------------------------
+ '.gz' 'gzip'
+ '.tgz' 'gzip'
+ '.taz' 'gzip'
+ '.Z' 'compress'
+ '.taZ' 'compress'
+ '.bz2' 'bzip2'
+ '.tz2' 'bzip2'
+ '.tbz2' 'bzip2'
+ '.tbz' 'bzip2'
+ '.lz' 'lzip'
+ '.lzma' 'lzma'
+ '.tlz' 'lzma'
+ '.lzo' 'lzop'
+ '.xz' 'xz'
+
+'--use-compress-program=COMMAND'
+'-I=COMMAND'
Use external compression program COMMAND. Use this option if you
- are not happy with the compression program associated with the
- suffix at compile time or if you have a compression program that
- GNU `tar' does not support. The COMMAND argument is a valid
- command invocation, as you would type it at the command line
- prompt, with any additional options as needed. Enclose it in
- quotes if it contains white space (see *note Running External
- Commands: external, for more detail).
+ want to specify options for the compression program, or if you are
+ not happy with the compression program associated with the suffix
+ at compile time, or if you have a compression program that GNU
+ 'tar' does not support. The COMMAND argument is a valid command
+ invocation, as you would type it at the command line prompt, with
+ any additional options as needed. Enclose it in quotes if it
+ contains white space (*note Running External Commands: external.).
The COMMAND should follow two conventions:
First, when invoked without additional options, it should read data
from standard input, compress it and output it on standard output.
- Secondly, if invoked with the additional `-d' option, it should do
+ Secondly, if invoked with the additional '-d' option, it should do
exactly the opposite, i.e., read the compressed data from the
standard input and produce uncompressed data on the standard
output.
- The latter requirement means that you must not use the `-d' option
+ The latter requirement means that you must not use the '-d' option
as a part of the COMMAND itself.
- The `--use-compress-program' option, in particular, lets you
+ The '--use-compress-program' option, in particular, lets you
implement your own filters, not necessarily dealing with
compression/decompression. For example, suppose you wish to implement
-PGP encryption on top of compression, using `gpg' (*note gpg:
+PGP encryption on top of compression, using 'gpg' (*note gpg:
(gpg)Top.). The following script does that:
#! /bin/sh
*) echo "Unknown option $1">&2; exit 1;;
esac
- Suppose you name it `gpgz' and save it somewhere in your `PATH'.
+ Suppose you name it 'gpgz' and save it somewhere in your 'PATH'.
Then the following command will create a compressed archive signed with
your private key:
* Menu:
-* lbzip2:: Using lbzip2 with GNU `tar'.
+* lbzip2:: Using lbzip2 with GNU 'tar'.
---------- Footnotes ----------
(1) It also had patent problems in the past.
(2) To verbosely trace the decompressor selection, use the
-`--warning=decompress-program' option (*note decompress-program:
+'--warning=decompress-program' option (*note decompress-program:
warnings.).
\1f
File: tar.info, Node: lbzip2, Up: gzip
-8.1.1.1 Using lbzip2 with GNU `tar'.
+8.1.1.1 Using lbzip2 with GNU 'tar'.
....................................
-`Lbzip2' is a multithreaded utility for handling `bzip2' compression,
+'Lbzip2' is a multithreaded utility for handling 'bzip2' compression,
written by Laszlo Ersek. It makes use of multiple processors to speed
-up its operation and in general works considerably faster than `bzip2'.
-For a detailed description of `lbzip2' see
-`http://freshmeat.net/projects/lbzip2' and lbzip2: parallel bzip2
+up its operation and in general works considerably faster than 'bzip2'.
+For a detailed description of 'lbzip2' see
+<http://freshmeat.net/projects/lbzip2> and lbzip2: parallel bzip2
utility
(http://www.linuxinsight.com/lbzip2-parallel-bzip2-utility.html).
- Recent versions of `lbzip2' are mostly command line compatible with
-`bzip2', which makes it possible to automatically invoke it via the
-`--bzip2' GNU `tar' command line option. To do so, GNU `tar' must be
-configured with the `--with-bzip2' command line option, like this:
+ Recent versions of 'lbzip2' are mostly command line compatible with
+'bzip2', which makes it possible to automatically invoke it via the
+'--bzip2' GNU 'tar' command line option. To do so, GNU 'tar' must be
+configured with the '--with-bzip2' command line option, like this:
$ ./configure --with-bzip2=lbzip2 [OTHER-OPTIONS]
- Once configured and compiled this way, `tar --help' will show the
+ Once configured and compiled this way, 'tar --help' will show the
following:
$ tar --help | grep -- --bzip2
-j, --bzip2 filter the archive through lbzip2
-which means that running `tar --bzip2' will invoke `lbzip2'.
+which means that running 'tar --bzip2' will invoke 'lbzip2'.
\1f
File: tar.info, Node: sparse, Prev: gzip, Up: Compression
is a section of the file's contents which was never written. The
contents of a hole reads as all zeros. On many operating systems,
actual disk storage is not allocated for holes, but they are counted in
-the length of the file. If you archive such a file, `tar' could create
-an archive longer than the original. To have `tar' attempt to
-recognize the holes in a file, use `--sparse' (`-S'). When you use
-this option, then, for any file using less disk space than would be
-expected from its length, `tar' searches the file for consecutive
-stretches of zeros. It then records in the archive for the file where
-the consecutive stretches of zeros are, and only archives the "real
-contents" of the file. On extraction (using `--sparse' is not needed
-on extraction) any such files have holes created wherever the
-continuous stretches of zeros were found. Thus, if you use `--sparse',
-`tar' archives won't take more space than the original.
-
-`-S'
-`--sparse'
- This option instructs `tar' to test each file for sparseness
- before attempting to archive it. If the file is found to be
- sparse it is treated specially, thus allowing to decrease the
- amount of space used by its image in the archive.
+the length of the file. If you archive such a file, 'tar' could create
+an archive longer than the original. To have 'tar' attempt to recognize
+the holes in a file, use '--sparse' ('-S'). When you use this option,
+then, for any file using less disk space than would be expected from its
+length, 'tar' searches the file for holes. It then records in the
+archive for the file where the holes (consecutive stretches of zeros)
+are, and only archives the "real contents" of the file. On extraction
+(using '--sparse' is not needed on extraction) any such files have also
+holes created wherever the holes were found. Thus, if you use
+'--sparse', 'tar' archives won't take more space than the original.
+
+ GNU 'tar' uses two methods for detecting holes in sparse files.
+These methods are described later in this subsection.
+
+'-S'
+'--sparse'
+ This option instructs 'tar' to test each file for sparseness before
+ attempting to archive it. If the file is found to be sparse it is
+ treated specially, thus allowing to decrease the amount of space
+ used by its image in the archive.
This option is meaningful only when creating or updating archives.
It has no effect on extraction.
- Consider using `--sparse' when performing file system backups, to
+ Consider using '--sparse' when performing file system backups, to
avoid archiving the expanded forms of files stored sparsely in the
system.
Even if your system has no sparse files currently, some may be
-created in the future. If you use `--sparse' while making file system
-backups as a matter of course, you can be assured the archive will
-never take more space on the media than the files take on disk
-(otherwise, archiving a disk filled with sparse files might take
-hundreds of tapes). *Note Incremental Dumps::.
-
- However, be aware that `--sparse' option presents a serious
-drawback. Namely, in order to determine if the file is sparse `tar'
-has to read it before trying to archive it, so in total the file is
-read *twice*. So, always bear in mind that the time needed to process
-all files with this option is roughly twice the time needed to archive
-them without it.
-
- When using `POSIX' archive format, GNU `tar' is able to store sparse
+created in the future. If you use '--sparse' while making file system
+backups as a matter of course, you can be assured the archive will never
+take more space on the media than the files take on disk (otherwise,
+archiving a disk filled with sparse files might take hundreds of tapes).
+*Note Incremental Dumps::.
+
+ However, be aware that '--sparse' option may present a serious
+drawback. Namely, in order to determine the positions of holes in a
+file 'tar' may have to read it before trying to archive it, so in total
+the file may be read *twice*. This may happen when your OS or your FS
+does not support "SEEK_HOLE/SEEK_DATA" feature in "lseek" (See
+'--hole-detection', below).
+
+ When using 'POSIX' archive format, GNU 'tar' is able to store sparse
files using in three distinct ways, called "sparse formats". A sparse
format is identified by its "number", consisting, as usual of two
-decimal numbers, delimited by a dot. By default, format `1.0' is used.
+decimal numbers, delimited by a dot. By default, format '1.0' is used.
If, for some reason, you wish to use an earlier format, you can select
-it using `--sparse-version' option.
+it using '--sparse-version' option.
-`--sparse-version=VERSION'
+'--sparse-version=VERSION'
Select the format to store sparse files in. Valid VERSION values
- are: `0.0', `0.1' and `1.0'. *Note Sparse Formats::, for a
+ are: '0.0', '0.1' and '1.0'. *Note Sparse Formats::, for a
detailed description of each format.
- Using `--sparse-format' option implies `--sparse'.
+ Using '--sparse-format' option implies '--sparse'.
+
+'--hole-detection=METHOD'
+ Enforce concrete hole detection method. Before the real contents
+ of sparse file are stored, 'tar' needs to gather knowledge about
+ file sparseness. This is because it needs to have the file's map
+ of holes stored into tar header before it starts archiving the file
+ contents. Currently, two methods of hole detection are
+ implemented:
+
+ * '--hole-detection=seek' Seeking the file for data and holes.
+ It uses enhancement of the 'lseek' system call ('SEEK_HOLE'
+ and 'SEEK_DATA') which is able to reuse file system knowledge
+ about sparse file contents - so the detection is usually very
+ fast. To use this feature, your file system and operating
+ system must support it. At the time of this writing (2015)
+ this feature, in spite of not being accepted by POSIX, is
+ fairly widely supported by different operating systems.
+
+ * '--hole-detection=raw' Reading byte-by-byte the whole sparse
+ file before the archiving. This method detects holes like
+ consecutive stretches of zeroes. Comparing to the previous
+ method, it is usually much slower, although more portable.
+
+ When no '--hole-detection' option is given, 'tar' uses the 'seek', if
+supported by the operating system.
+
+ Using '--hole-detection' option implies '--sparse'.
\1f
File: tar.info, Node: Attributes, Next: Portability, Prev: Compression, Up: Formats
8.2 Handling File Attributes
============================
-When `tar' reads files, it updates their access times. To avoid this,
-use the `--atime-preserve[=METHOD]' option, which can either reset the
+When 'tar' reads files, it updates their access times. To avoid this,
+use the '--atime-preserve[=METHOD]' option, which can either reset the
access time retroactively or avoid changing it in the first place.
-`--atime-preserve'
-`--atime-preserve=replace'
-`--atime-preserve=system'
+'--atime-preserve'
+'--atime-preserve=replace'
+'--atime-preserve=system'
Preserve the access times of files that are read. This works only
for files that you own, unless you have superuser privileges.
- `--atime-preserve=replace' works on most systems, but it also
+ '--atime-preserve=replace' works on most systems, but it also
restores the data modification time and updates the status change
time. Hence it doesn't interact with incremental dumps nicely
(*note Incremental Dumps::), and it can set access or data
modification times incorrectly if other programs access the file
- while `tar' is running.
+ while 'tar' is running.
- `--atime-preserve=system' avoids changing the access time in the
- first place, if the operating system supports this.
- Unfortunately, this may or may not work on any given operating
- system or file system. If `tar' knows for sure it won't work, it
- complains right away.
+ '--atime-preserve=system' avoids changing the access time in the
+ first place, if the operating system supports this. Unfortunately,
+ this may or may not work on any given operating system or file
+ system. If 'tar' knows for sure it won't work, it complains right
+ away.
- Currently `--atime-preserve' with no operand defaults to
- `--atime-preserve=replace', but this is intended to change to
- `--atime-preserve=system' when the latter is better-supported.
+ Currently '--atime-preserve' with no operand defaults to
+ '--atime-preserve=replace', but this is intended to change to
+ '--atime-preserve=system' when the latter is better-supported.
-`-m'
-`--touch'
+'-m'
+'--touch'
Do not extract data modification time.
- When this option is used, `tar' leaves the data modification times
+ When this option is used, 'tar' leaves the data modification times
of the files it extracts as the times when the files were
extracted, instead of setting it to the times recorded in the
archive.
- This option is meaningless with `--list' (`-t').
+ This option is meaningless with '--list' ('-t').
-`--same-owner'
+'--same-owner'
Create extracted files with the same ownership they have in the
archive.
This is the default behavior for the superuser, so this option is
- meaningful only for non-root users, when `tar' is executed on
- those systems able to give files away. This is considered as a
- security flaw by many people, at least because it makes quite
- difficult to correctly account users for the disk space they
- occupy. Also, the `suid' or `sgid' attributes of files are easily
- and silently lost when files are given away.
-
- When writing an archive, `tar' writes the user ID and user name
+ meaningful only for non-root users, when 'tar' is executed on those
+ systems able to give files away. This is considered as a security
+ flaw by many people, at least because it makes quite difficult to
+ correctly account users for the disk space they occupy. Also, the
+ 'suid' or 'sgid' attributes of files are easily and silently lost
+ when files are given away.
+
+ When writing an archive, 'tar' writes the user ID and user name
separately. If it can't find a user name (because the user ID is
- not in `/etc/passwd'), then it does not write one. When restoring,
- it tries to look the name (if one was written) up in
- `/etc/passwd'. If it fails, then it uses the user ID stored in
- the archive instead.
+ not in '/etc/passwd'), then it does not write one. When restoring,
+ it tries to look the name (if one was written) up in '/etc/passwd'.
+ If it fails, then it uses the user ID stored in the archive
+ instead.
-`--no-same-owner'
-`-o'
+'--no-same-owner'
+'-o'
Do not attempt to restore ownership when extracting. This is the
default behavior for ordinary users, so this option has an effect
only for the superuser.
-`--numeric-owner'
- The `--numeric-owner' option allows (ANSI) archives to be written
+'--numeric-owner'
+ The '--numeric-owner' option allows (ANSI) archives to be written
without user/group name information or such information to be
ignored when extracting. It effectively disables the generation
and/or use of user/group name information. This option forces
with no password file or put your disk into another machine to do
the restore.
- The numeric ids are _always_ saved into `tar' archives. The
+ The numeric ids are _always_ saved into 'tar' archives. The
identifying names are added at create time when provided by the
- system, unless `--format=oldgnu' is used. Numeric ids could be
+ system, unless '--format=oldgnu' is used. Numeric ids could be
used when moving archives between a collection of machines using a
centralized management for attribution of numeric ids to users and
groups. This is often made through using the NIS capabilities.
- When making a `tar' file for distribution to other sites, it is
+ When making a 'tar' file for distribution to other sites, it is
sometimes cleaner to use a single owner for all files in the
distribution, and nicer to specify the write permission bits of the
files as stored in the archive independently of their actual value
usually to have some Makefile rule creating a directory, copying
all needed files in that directory, then setting ownership and
permissions as wanted (there are a lot of possible schemes), and
- only then making a `tar' archive out of this directory, before
+ only then making a 'tar' archive out of this directory, before
cleaning everything out. Of course, we could add a lot of options
- to GNU `tar' for fine tuning permissions and ownership. This is
- not the good way, I think. GNU `tar' is already crowded with
- options and moreover, the approach just explained gives you a
- great deal of control already.
-
-`-p'
-`--same-permissions'
-`--preserve-permissions'
+ to GNU 'tar' for fine tuning permissions and ownership. This is
+ not the good way, I think. GNU 'tar' is already crowded with
+ options and moreover, the approach just explained gives you a great
+ deal of control already.
+
+'-p'
+'--same-permissions'
+'--preserve-permissions'
Extract all protection information.
- This option causes `tar' to set the modes (access permissions) of
+ This option causes 'tar' to set the modes (access permissions) of
extracted files exactly as recorded in the archive. If this option
- is not used, the current `umask' setting limits the permissions on
- extracted files. This option is by default enabled when `tar' is
+ is not used, the current 'umask' setting limits the permissions on
+ extracted files. This option is by default enabled when 'tar' is
executed by a superuser.
- This option is meaningless with `--list' (`-t').
-
-`--preserve'
- Same as both `--same-permissions' and `--same-order'.
-
- This option is deprecated, and will be removed in GNU `tar'
- version 1.23.
-
+ This option is meaningless with '--list' ('-t').
\1f
File: tar.info, Node: Portability, Next: cpio, Prev: Attributes, Up: Formats
-8.3 Making `tar' Archives More Portable
+8.3 Making 'tar' Archives More Portable
=======================================
-Creating a `tar' archive on a particular system that is meant to be
-useful later on many other machines and with other versions of `tar' is
-more challenging than you might think. `tar' archive formats have been
+Creating a 'tar' archive on a particular system that is meant to be
+useful later on many other machines and with other versions of 'tar' is
+more challenging than you might think. 'tar' archive formats have been
evolving since the first versions of Unix. Many such formats are
around, and are not always compatible with each other. This section
-discusses a few problems, and gives some advice about making `tar'
+discusses a few problems, and gives some advice about making 'tar'
archives more portable.
- One golden rule is simplicity. For example, limit your `tar'
+ One golden rule is simplicity. For example, limit your 'tar'
archives to contain only regular files and directories, avoiding other
kind of special files. Do not attempt to save sparse files or
contiguous files as such. Let's discuss a few more problems, in turn.
* Checksumming:: Checksumming Problems
* Large or Negative Values:: Large files, negative time stamps, etc.
* Other Tars:: How to Extract GNU-Specific Data Using
- Other `tar' Implementations
+ Other 'tar' Implementations
\1f
File: tar.info, Node: Portable Names, Next: dereference, Up: Portability
--------------------
Use portable file and member names. A name is portable if it contains
-only ASCII letters and digits, `/', `.', `_', and `-'; it cannot be
-empty, start with `-' or `//', or contain `/-'. Avoid deep directory
+only ASCII letters and digits, '/', '.', '_', and '-'; it cannot be
+empty, start with '-' or '//', or contain '/-'. Avoid deep directory
nesting. For portability to old Unix hosts, limit your file name
components to 14 characters or less.
- If you intend to have your `tar' archives to be read under MSDOS,
-you should not rely on case distinction for file names, and you might
-use the GNU `doschk' program for helping you further diagnosing illegal
+ If you intend to have your 'tar' archives to be read under MSDOS, you
+should not rely on case distinction for file names, and you might use
+the GNU 'doschk' program for helping you further diagnosing illegal
MSDOS names, which are even more limited than System V's.
\1f
8.3.2 Symbolic Links
--------------------
-Normally, when `tar' archives a symbolic link, it writes a block to the
-archive naming the target of the link. In that way, the `tar' archive
-is a faithful record of the file system contents. When `--dereference'
-(`-h') is used with `--create' (`-c'), `tar' archives the files
-symbolic links point to, instead of the links themselves.
+Normally, when 'tar' archives a symbolic link, it writes a block to the
+archive naming the target of the link. In that way, the 'tar' archive
+is a faithful record of the file system contents. When '--dereference'
+('-h') is used with '--create' ('-c'), 'tar' archives the files symbolic
+links point to, instead of the links themselves.
- When creating portable archives, use `--dereference' (`-h'): some
+ When creating portable archives, use '--dereference' ('-h'): some
systems do not support symbolic links, and moreover, your distribution
might be unusable if it contains unresolved symbolic links.
- When reading from an archive, the `--dereference' (`-h') option
-causes `tar' to follow an already-existing symbolic link when `tar'
-writes or reads a file named in the archive. Ordinarily, `tar' does
-not follow such a link, though it may remove the link before writing a
-new file. *Note Dealing with Old Files::.
+ When reading from an archive, the '--dereference' ('-h') option
+causes 'tar' to follow an already-existing symbolic link when 'tar'
+writes or reads a file named in the archive. Ordinarily, 'tar' does not
+follow such a link, though it may remove the link before writing a new
+file. *Note Dealing with Old Files::.
- The `--dereference' option is unsafe if an untrusted user can modify
-directories while `tar' is running. *Note Security::.
+ The '--dereference' option is unsafe if an untrusted user can modify
+directories while 'tar' is running. *Note Security::.
\1f
File: tar.info, Node: hard links, Next: old, Prev: dereference, Up: Portability
8.3.3 Hard Links
----------------
-Normally, when `tar' archives a hard link, it writes a block to the
-archive naming the target of the link (a `1' type block). In that way,
+Normally, when 'tar' archives a hard link, it writes a block to the
+archive naming the target of the link (a '1' type block). In that way,
the actual file contents is stored in file only once. For example,
consider the following two files:
-rw-r--r-- 2 gray staff 4 2007-10-30 15:11 one
-rw-r--r-- 2 gray staff 4 2007-10-30 15:11 jeden
- Here, `jeden' is a link to `one'. When archiving this directory
-with a verbose level 2, you will get an output similar to the following:
+ Here, 'jeden' is a link to 'one'. When archiving this directory with
+a verbose level 2, you will get an output similar to the following:
$ tar cvvf ../archive.tar .
drwxr-xr-x gray/staff 0 2007-10-30 15:13 ./
hrw-r--r-- gray/staff 0 2007-10-30 15:11 ./one link to ./jeden
The last line shows that, instead of storing two copies of the file,
-`tar' stored it only once, under the name `jeden', and stored file
-`one' as a hard link to this file.
+'tar' stored it only once, under the name 'jeden', and stored file 'one'
+as a hard link to this file.
It may be important to know that all hard links to the given file are
stored in the archive. For example, this may be necessary for exact
reproduction of the file system. The following option does that:
-`--check-links'
-`-l'
+'--check-links'
+'-l'
Check the number of links dumped for each processed file. If this
number does not match the total number of hard links for the file,
print a warning message.
- For example, trying to archive only file `jeden' with this option
+ For example, trying to archive only file 'jeden' with this option
produces the following diagnostics:
$ tar -c -f ../archive.tar -l jeden
Although creating special records for hard links helps keep a
faithful record of the file system contents and makes archives more
compact, it may present some difficulties when extracting individual
-members from the archive. For example, trying to extract file `one'
-from the archive created in previous examples produces, in the absense
-of file `jeden':
+members from the archive. For example, trying to extract file 'one'
+from the archive created in previous examples produces, in the absence
+of file 'jeden':
$ tar xf archive.tar ./one
tar: ./one: Cannot hard link to './jeden': No such file or directory
tar: Error exit delayed from previous errors
- The reason for this behavior is that `tar' cannot seek back in the
-archive to the previous member (in this case, `one'), to extract it(1).
+ The reason for this behavior is that 'tar' cannot seek back in the
+archive to the previous member (in this case, 'one'), to extract it(1).
If you wish to avoid such problems at the cost of a bigger archive, use
the following option:
-`--hard-dereference'
+'--hard-dereference'
Dereference hard links and store the files they refer to.
For example, trying this option on our two sample files, we get two
-copies in the archive, each of which can then be extracted
-independently of the other:
+copies in the archive, each of which can then be extracted independently
+of the other:
$ tar -c -vv -f ../archive.tar --hard-dereference .
drwxr-xr-x gray/staff 0 2007-10-30 15:13 ./
8.3.4 Old V7 Archives
---------------------
-Certain old versions of `tar' cannot handle additional information
-recorded by newer `tar' programs. To create an archive in V7 format
+Certain old versions of 'tar' cannot handle additional information
+recorded by newer 'tar' programs. To create an archive in V7 format
(not ANSI), which can be read by these old versions, specify the
-`--format=v7' option in conjunction with the `--create' (`-c') (`tar'
-also accepts `--portability' or `--old-archive' for this option). When
-you specify it, `tar' leaves out information about directories, pipes,
+'--format=v7' option in conjunction with the '--create' ('-c') ('tar'
+also accepts '--portability' or '--old-archive' for this option). When
+you specify it, 'tar' leaves out information about directories, pipes,
fifos, contiguous files, and device files, and specifies file ownership
by group and user IDs instead of group and user names.
- When updating an archive, do not use `--format=v7' unless the
-archive was created using this option.
+ When updating an archive, do not use '--format=v7' unless the archive
+was created using this option.
- In most cases, a _new_ format archive can be read by an _old_ `tar'
-program without serious trouble, so this option should seldom be
-needed. On the other hand, most modern `tar's are able to read old
-format archives, so it might be safer for you to always use
-`--format=v7' for your distributions. Notice, however, that `ustar'
-format is a better alternative, as it is free from many of `v7''s
-drawbacks.
+ In most cases, a _new_ format archive can be read by an _old_ 'tar'
+program without serious trouble, so this option should seldom be needed.
+On the other hand, most modern 'tar's are able to read old format
+archives, so it might be safer for you to always use '--format=v7' for
+your distributions. Notice, however, that 'ustar' format is a better
+alternative, as it is free from many of 'v7''s drawbacks.
\1f
File: tar.info, Node: ustar, Next: gnu, Prev: old, Up: Portability
--------------------------
The archive format defined by the POSIX.1-1988 specification is called
-`ustar'. Although it is more flexible than the V7 format, it still has
-many restrictions (*note ustar: Formats, for the detailed description
-of `ustar' format). Along with V7 format, `ustar' format is a good
-choice for archives intended to be read with other implementations of
-`tar'.
+'ustar'. Although it is more flexible than the V7 format, it still has
+many restrictions (*note ustar: Formats, for the detailed description of
+'ustar' format). Along with V7 format, 'ustar' format is a good choice
+for archives intended to be read with other implementations of 'tar'.
- To create an archive in `ustar' format, use the `--format=ustar'
-option in conjunction with `--create' (`-c').
+ To create an archive in 'ustar' format, use the '--format=ustar'
+option in conjunction with '--create' ('-c').
\1f
File: tar.info, Node: gnu, Next: posix, Prev: ustar, Up: Portability
-8.3.6 GNU and old GNU `tar' format
+8.3.6 GNU and old GNU 'tar' format
----------------------------------
-GNU `tar' was based on an early draft of the POSIX 1003.1 `ustar'
-standard. GNU extensions to `tar', such as the support for file names
-longer than 100 characters, use portions of the `tar' header record
+GNU 'tar' was based on an early draft of the POSIX 1003.1 'ustar'
+standard. GNU extensions to 'tar', such as the support for file names
+longer than 100 characters, use portions of the 'tar' header record
which were specified in that POSIX draft as unused. Subsequent changes
in POSIX have allocated the same parts of the header record for other
-purposes. As a result, GNU `tar' format is incompatible with the
-current POSIX specification, and with `tar' programs that follow it.
+purposes. As a result, GNU 'tar' format is incompatible with the
+current POSIX specification, and with 'tar' programs that follow it.
- In the majority of cases, `tar' will be configured to create this
+ In the majority of cases, 'tar' will be configured to create this
format by default. This will change in future releases, since we plan
-to make `POSIX' format the default.
+to make 'POSIX' format the default.
- To force creation a GNU `tar' archive, use option `--format=gnu'.
+ To force creation a GNU 'tar' archive, use option '--format=gnu'.
\1f
File: tar.info, Node: posix, Next: Checksumming, Prev: gnu, Up: Portability
-8.3.7 GNU `tar' and POSIX `tar'
+8.3.7 GNU 'tar' and POSIX 'tar'
-------------------------------
-Starting from version 1.14 GNU `tar' features full support for
+Starting from version 1.14 GNU 'tar' features full support for
POSIX.1-2001 archives.
- A POSIX conformant archive will be created if `tar' was given
-`--format=posix' (`--format=pax') option. No special option is
-required to read and extract from a POSIX archive.
+ A POSIX conformant archive will be created if 'tar' was given
+'--format=posix' ('--format=pax') option. No special option is required
+to read and extract from a POSIX archive.
* Menu:
8.3.7.1 Controlling Extended Header Keywords
............................................
-`--pax-option=KEYWORD-LIST'
- Handle keywords in PAX extended headers. This option is
- equivalent to `-o' option of the `pax' utility.
+'--pax-option=KEYWORD-LIST'
+ Handle keywords in PAX extended headers. This option is equivalent
+ to '-o' option of the 'pax' utility.
KEYWORD-LIST is a comma-separated list of keyword options, each
keyword option taking one of the following forms:
-`delete=PATTERN'
+'delete=PATTERN'
When used with one of archive-creation commands, this option
- instructs `tar' to omit from extended header records that it
+ instructs 'tar' to omit from extended header records that it
produces any keywords matching the string PATTERN.
When used in extract or list mode, this option instructs tar to
would suppress security-related information.
-`exthdr.name=STRING'
- This keyword allows user control over the name that is written
- into the ustar header blocks for the extended headers. The name
- is obtained from STRING after making the following substitutions:
-
- Meta-character Replaced By
- --------------------------------------------------------
- %d The directory name of the file,
- equivalent to the result of the
- `dirname' utility on the translated
- file name.
- %f The name of the file with the
- directory information stripped,
- equivalent to the result of the
- `basename' utility on the translated
- file name.
- %p The process ID of the `tar' process.
- %% A `%' character.
-
- Any other `%' characters in STRING produce undefined results.
-
- If no option `exthdr.name=string' is specified, `tar' will use the
+'exthdr.name=STRING'
+
+ This keyword allows user control over the name that is written into
+ the ustar header blocks for the extended headers. The name is
+ obtained from STRING after making the following substitutions:
+
+ Meta-character Replaced By
+ ------------------------------------------------------------
+ %d The directory name of the file,
+ equivalent to the result of the
+ 'dirname' utility on the translated
+ file name.
+ %f The name of the file with the
+ directory information stripped,
+ equivalent to the result of the
+ 'basename' utility on the translated
+ file name.
+ %p The process ID of the 'tar' process.
+ %% A '%' character.
+
+ Any other '%' characters in STRING produce undefined results.
+
+ If no option 'exthdr.name=string' is specified, 'tar' will use the
following default value:
%d/PaxHeaders.%p/%f
-`exthdr.mtime=VALUE'
- This keyword defines the value of the `mtime' field that is
- written into the ustar header blocks for the extended headers. By
- default, the `mtime' field is set to the modification time of the
- archive member described by that extended headers.
+'exthdr.mtime=VALUE'
-`globexthdr.name=STRING'
+ This keyword defines the value of the 'mtime' field that is written
+ into the ustar header blocks for the extended headers. By default,
+ the 'mtime' field is set to the modification time of the archive
+ member described by that extended header (or to the value of the
+ '--mtime' option, if supplied).
+
+'globexthdr.name=STRING'
This keyword allows user control over the name that is written into
the ustar header blocks for global extended header records. The
name is obtained from the contents of STRING, after making the
following substitutions:
- Meta-character Replaced By
- --------------------------------------------------------
- %n An integer that represents the
- sequence number of the global
- extended header record in the
- archive, starting at 1.
- %p The process ID of the `tar' process.
- %% A `%' character.
+ Meta-character Replaced By
+ ------------------------------------------------------------
+ %n An integer that represents the
+ sequence number of the global extended
+ header record in the archive, starting
+ at 1.
+ %p The process ID of the 'tar' process.
+ %% A '%' character.
- Any other `%' characters in STRING produce undefined results.
+ Any other '%' characters in STRING produce undefined results.
- If no option `globexthdr.name=string' is specified, `tar' will use
+ If no option 'globexthdr.name=string' is specified, 'tar' will use
the following default value:
$TMPDIR/GlobalHead.%p.%n
- where `$TMPDIR' represents the value of the TMPDIR environment
- variable. If TMPDIR is not set, `tar' uses `/tmp'.
+ where '$TMPDIR' represents the value of the TMPDIR environment
+ variable. If TMPDIR is not set, 'tar' uses '/tmp'.
+
+'globexthdr.mtime=VALUE'
-`globexthdr.mtime=VALUE'
- This keyword defines the value of the `mtime' field that is
- written into the ustar header blocks for the global extended
- headers. By default, the `mtime' field is set to the time when
- `tar' was invoked.
+ This keyword defines the value of the 'mtime' field that is written
+ into the ustar header blocks for the global extended headers. By
+ default, the 'mtime' field is set to the time when 'tar' was
+ invoked.
-`KEYWORD=VALUE'
+'KEYWORD=VALUE'
When used with one of archive-creation commands, these
keyword/value pairs will be included at the beginning of the
archive in a global extended header record. When used with one of
- archive-reading commands, `tar' will behave as if it has
+ archive-reading commands, 'tar' will behave as if it has
encountered these keyword/value pairs at the beginning of the
archive in a global extended header record.
-`KEYWORD:=VALUE'
+'KEYWORD:=VALUE'
When used with one of archive-creation commands, these
- keyword/value pairs will be included as records at the beginning
- of an extended header for each file. This is effectively
- equivalent to KEYWORD=VALUE form except that it creates no global
- extended header records.
-
- When used with one of archive-reading commands, `tar' will behave
- as if these keyword/value pairs were included as records at the
- end of each extended header; thus, they will override any global or
+ keyword/value pairs will be included as records at the beginning of
+ an extended header for each file. This is effectively equivalent
+ to KEYWORD=VALUE form except that it creates no global extended
+ header records.
+
+ When used with one of archive-reading commands, 'tar' will behave
+ as if these keyword/value pairs were included as records at the end
+ of each extended header; thus, they will override any global or
file-specific extended header record keywords of the same names.
For example, in the command:
enclosed in curly braces. In that case, the string between the braces
is understood either as a textual time representation, as described in
*note Date input formats::, or a name of the existing file, starting
-with `/' or `.'. In the latter case, the modification time of that
-file is used.
+with '/' or '.'. In the latter case, the modification time of that file
+is used.
For example, to set all modification times to the current date, you
use the following option:
--pax-option=exthdr.name=%d/PaxHeaders/%f,atime:=0
+If you extract files from such an archive and recreate the archive from
+them, you will also need to eliminate changes due to ctime, as shown in
+examples below:
+
+ --pax-option=exthdr.name=%d/PaxHeaders/%f,atime:=0,ctime:=0
+
+or
+
+ --pax-option=exthdr.name=%d/PaxHeaders/%f,atime:=0,delete=ctime
+
\1f
File: tar.info, Node: Checksumming, Next: Large or Negative Values, Prev: posix, Up: Portability
8.3.8 Checksumming Problems
---------------------------
-SunOS and HP-UX `tar' fail to accept archives created using GNU `tar'
+SunOS and HP-UX 'tar' fail to accept archives created using GNU 'tar'
and containing non-ASCII file names, that is, file names having
characters with the eighth bit set, because they use signed checksums,
-while GNU `tar' uses unsigned checksums while creating archives, as per
-POSIX standards. On reading, GNU `tar' computes both checksums and
+while GNU 'tar' uses unsigned checksums while creating archives, as per
+POSIX standards. On reading, GNU 'tar' computes both checksums and
accepts either of them. It is somewhat worrying that a lot of people
may go around doing backup of their files using faulty (or at least
-non-standard) software, not learning about it until it's time to
-restore their missing files with an incompatible file extractor, or
-vice versa.
-
- GNU `tar' computes checksums both ways, and accepts either of them
-on read, so GNU tar can read Sun tapes even with their wrong checksums.
-GNU `tar' produces the standard checksum, however, raising
-incompatibilities with Sun. That is to say, GNU `tar' has not been
-modified to _produce_ incorrect archives to be read by buggy `tar''s.
-I've been told that more recent Sun `tar' now read standard archives,
-so maybe Sun did a similar patch, after all?
-
- The story seems to be that when Sun first imported `tar' sources on
+non-standard) software, not learning about it until it's time to restore
+their missing files with an incompatible file extractor, or vice versa.
+
+ GNU 'tar' computes checksums both ways, and accepts either of them on
+read, so GNU tar can read Sun tapes even with their wrong checksums.
+GNU 'tar' produces the standard checksum, however, raising
+incompatibilities with Sun. That is to say, GNU 'tar' has not been
+modified to _produce_ incorrect archives to be read by buggy 'tar''s.
+I've been told that more recent Sun 'tar' now read standard archives, so
+maybe Sun did a similar patch, after all?
+
+ The story seems to be that when Sun first imported 'tar' sources on
their system, they recompiled it without realizing that the checksums
-were computed differently, because of a change in the default signing
-of `char''s in their compiler. So they started computing checksums
-wrongly. When they later realized their mistake, they merely decided
-to stay compatible with it, and with themselves afterwards.
-Presumably, but I do not really know, HP-UX has chosen their `tar'
-archives to be compatible with Sun's. The current standards do not
-favor Sun `tar' format. In any case, it now falls on the shoulders of
-SunOS and HP-UX users to get a `tar' able to read the good archives
-they receive.
+were computed differently, because of a change in the default signing of
+'char''s in their compiler. So they started computing checksums
+wrongly. When they later realized their mistake, they merely decided to
+stay compatible with it, and with themselves afterwards. Presumably,
+but I do not really know, HP-UX has chosen their 'tar' archives to be
+compatible with Sun's. The current standards do not favor Sun 'tar'
+format. In any case, it now falls on the shoulders of SunOS and HP-UX
+users to get a 'tar' able to read the good archives they receive.
\1f
File: tar.info, Node: Large or Negative Values, Next: Other Tars, Prev: Checksumming, Up: Portability
_(This message will disappear, once this node revised.)_
-The above sections suggest to use `oldest possible' archive format if
+ The above sections suggest to use 'oldest possible' archive format if
in doubt. However, sometimes it is not possible. If you attempt to
archive a file whose metadata cannot be represented using required
-format, GNU `tar' will print error message and ignore such a file. You
-will than have to switch to a format that is able to handle such
-values. The format summary table (*note Formats::) will help you to do
-so.
+format, GNU 'tar' will print error message and ignore such a file. You
+will than have to switch to a format that is able to handle such values.
+The format summary table (*note Formats::) will help you to do so.
In particular, when trying to archive files larger than 8GB or with
timestamps not in the range 1970-01-01 00:00:00 through 2242-03-16
12:56:31 UTC, you will have to chose between GNU and POSIX archive
-formats. When considering which format to choose, bear in mind that
-the GNU format uses two's-complement base-256 notation to store values
-that do not fit into standard ustar range. Such archives can generally
-be read only by a GNU `tar' implementation. Moreover, they sometimes
-cannot be correctly restored on another hosts even by GNU `tar'. For
+formats. When considering which format to choose, bear in mind that the
+GNU format uses two's-complement base-256 notation to store values that
+do not fit into standard ustar range. Such archives can generally be
+read only by a GNU 'tar' implementation. Moreover, they sometimes
+cannot be correctly restored on another hosts even by GNU 'tar'. For
example, using two's complement representation for negative time stamps
-that assumes a signed 32-bit `time_t' generates archives that are not
-portable to hosts with differing `time_t' representations.
+that assumes a signed 32-bit 'time_t' generates archives that are not
+portable to hosts with differing 'time_t' representations.
On the other hand, POSIX archives, generally speaking, can be
-extracted by any tar implementation that understands older ustar
-format. The only exception are files larger than 8GB.
+extracted by any tar implementation that understands older ustar format.
+The only exception are files larger than 8GB.
\1f
File: tar.info, Node: Other Tars, Prev: Large or Negative Values, Up: Portability
-8.3.10 How to Extract GNU-Specific Data Using Other `tar' Implementations
+8.3.10 How to Extract GNU-Specific Data Using Other 'tar' Implementations
-------------------------------------------------------------------------
-In previous sections you became acquainted with various quirks
-necessary to make your archives portable. Sometimes you may need to
-extract archives containing GNU-specific members using some third-party
-`tar' implementation or an older version of GNU `tar'. Of course your
-best bet is to have GNU `tar' installed, but if it is for some reason
+In previous sections you became acquainted with various quirks necessary
+to make your archives portable. Sometimes you may need to extract
+archives containing GNU-specific members using some third-party 'tar'
+implementation or an older version of GNU 'tar'. Of course your best
+bet is to have GNU 'tar' installed, but if it is for some reason
impossible, this section will explain how to cope without it.
When we speak about "GNU-specific" members we mean two classes of
them: members split between the volumes of a multi-volume archive and
sparse members. You will be able to always recover such members if the
archive is in PAX format. In addition split members can be recovered
-from archives in old GNU format. The following subsections describe
-the required procedures in detail.
+from archives in old GNU format. The following subsections describe the
+required procedures in detail.
* Menu:
.................................................
If a member is split between several volumes of an old GNU format
-archive most third party `tar' implementation will fail to extract it.
-To extract it, use `tarcat' program (*note Tarcat::). This program is
-available from GNU `tar' home page
+archive most third party 'tar' implementation will fail to extract it.
+To extract it, use 'tarcat' program (*note Tarcat::). This program is
+available from GNU 'tar' home page
(http://www.gnu.org/software/tar/utils/tarcat.html). It concatenates
several archive volumes into a single valid archive. For example, if
-you have three volumes named from `vol-1.tar' to `vol-3.tar', you can
-do the following to extract them using a third-party `tar':
+you have three volumes named from 'vol-1.tar' to 'vol-3.tar', you can do
+the following to extract them using a third-party 'tar':
$ tarcat vol-1.tar vol-2.tar vol-3.tar | tar xf -
You could use this approach for most (although not all) PAX format
archives as well. However, extracting split members from a PAX archive
-is a much easier task, because PAX volumes are constructed in such a
-way that each part of a split member is extracted to a different file
-by `tar' implementations that are not aware of GNU extensions. More
+is a much easier task, because PAX volumes are constructed in such a way
+that each part of a split member is extracted to a different file by
+'tar' implementations that are not aware of GNU extensions. More
specifically, the very first part retains its original name, and all
subsequent parts are named using the pattern:
%d/GNUFileParts.%p/%f.%n
-where symbols preceeded by `%' are "macro characters" that have the
+where symbols preceded by '%' are "macro characters" that have the
following meaning:
Meta-character Replaced By
-------------------------------------------------------------
+------------------------------------------------------------
%d The directory name of the file,
equivalent to the result of the
- `dirname' utility on its full name.
+ 'dirname' utility on its full name.
%f The file name of the file, equivalent
- to the result of the `basename' utility
- on its full name.
-%p The process ID of the `tar' process that
- created the archive.
-%n Ordinal number of this particular part.
+ to the result of the 'basename'
+ utility on its full name.
+%p The process ID of the 'tar' process
+ that created the archive.
+%n Ordinal number of this particular
+ part.
- For example, if the file `var/longfile' was split during archive
-creation between three volumes, and the creator `tar' process had
-process ID `27962', then the member names will be:
+ For example, if the file 'var/longfile' was split during archive
+creation between three volumes, and the creator 'tar' process had
+process ID '27962', then the member names will be:
var/longfile
var/GNUFileParts.27962/longfile.1
var/GNUFileParts.27962/longfile.2
- When you extract your archive using a third-party `tar', these files
+ When you extract your archive using a third-party 'tar', these files
will be created on your disk, and the only thing you will need to do to
-restore your file in its original form is concatenate them in the
-proper order, for example:
+restore your file in its original form is concatenate them in the proper
+order, for example:
$ cd var
$ cat GNUFileParts.27962/longfile.1 \
GNUFileParts.27962/longfile.2 >> longfile
$ rm -f GNUFileParts.27962
- Notice, that if the `tar' implementation you use supports PAX format
+ Notice, that if the 'tar' implementation you use supports PAX format
archives, it will probably emit warnings about unknown keywords during
extraction. They will look like this:
You can safely ignore these warnings.
- If your `tar' implementation is not PAX-aware, you will get more
+ If your 'tar' implementation is not PAX-aware, you will get more
warnings and more files generated on your disk, e.g.:
$ tar xf vol-1.tar
GNUFileParts.27962/PaxHeaders.27962/sparsefile.1: Unknown file type
'x', extracted as normal file
- Ignore these warnings. The `PaxHeaders.*' directories created will
+ Ignore these warnings. The 'PaxHeaders.*' directories created will
contain files with "extended header keywords" describing the extracted
files. You can delete them, unless they describe sparse members. Read
further to learn more about them.
8.3.10.2 Extracting Sparse Members
..................................
-Any `tar' implementation will be able to extract sparse members from a
+Any 'tar' implementation will be able to extract sparse members from a
PAX archive. However, the extracted files will be "condensed", i.e.,
any zero blocks will be removed from them. When we restore such a
condensed file to its original form, by adding zero blocks (or "holes")
compressed sparse file.
To expand a file, you will need a simple auxiliary program called
-`xsparse'. It is available in source form from GNU `tar' home page
+'xsparse'. It is available in source form from GNU 'tar' home page
(http://www.gnu.org/software/tar/utils/xsparse.html).
Let's begin with archive members in "sparse format version 1.0"(1),
which are the easiest to expand. The condensed file will contain both
file map and file data, so no additional data will be needed to restore
-it. If the original file name was `DIR/NAME', then the condensed file
-will be named `DIR/GNUSparseFile.N/NAME', where N is a decimal
+it. If the original file name was 'DIR/NAME', then the condensed file
+will be named 'DIR/GNUSparseFile.N/NAME', where N is a decimal
number(2).
- To expand a version 1.0 file, run `xsparse' as follows:
+ To expand a version 1.0 file, run 'xsparse' as follows:
- $ xsparse `cond-file'
+ $ xsparse cond-file
-where `cond-file' is the name of the condensed file. The utility will
+where 'cond-file' is the name of the condensed file. The utility will
deduce the name for the resulting expanded file using the following
algorithm:
- 1. If `cond-file' does not contain any directories, `../cond-file'
+ 1. If 'cond-file' does not contain any directories, '../cond-file'
will be used;
- 2. If `cond-file' has the form `DIR/T/NAME', where both T and NAME
- are simple names, with no `/' characters in them, the output file
- name will be `DIR/NAME'.
+ 2. If 'cond-file' has the form 'DIR/T/NAME', where both T and NAME are
+ simple names, with no '/' characters in them, the output file name
+ will be 'DIR/NAME'.
- 3. Otherwise, if `cond-file' has the form `DIR/NAME', the output file
- name will be `NAME'.
+ 3. Otherwise, if 'cond-file' has the form 'DIR/NAME', the output file
+ name will be 'NAME'.
In the unlikely case when this algorithm does not suit your needs,
you can explicitly specify output file name as a second argument to the
command:
- $ xsparse `cond-file' `out-file'
+ $ xsparse cond-file out-file
- It is often a good idea to run `xsparse' in "dry run" mode first.
-In this mode, the command does not actually expand the file, but
-verbosely lists all actions it would be taking to do so. The dry run
-mode is enabled by `-n' command line argument:
+ It is often a good idea to run 'xsparse' in "dry run" mode first. In
+this mode, the command does not actually expand the file, but verbosely
+lists all actions it would be taking to do so. The dry run mode is
+enabled by '-n' command line argument:
$ xsparse -n /home/gray/GNUSparseFile.6058/sparsefile
Reading v.1.0 sparse map
$ xsparse /home/gray/GNUSparseFile.6058/sparsefile
The program behaves the same way all UNIX utilities do: it will keep
-quiet unless it has simething important to tell you (e.g. an error
+quiet unless it has something important to tell you (e.g. an error
condition or something). If you wish it to produce verbose output,
-similar to that from the dry run mode, use `-v' option:
+similar to that from the dry run mode, use '-v' option:
$ xsparse -v /home/gray/GNUSparseFile.6058/sparsefile
Reading v.1.0 sparse map
'/home/gray/sparsefile'
Done
- Additionally, if your `tar' implementation has extracted the
-"extended headers" for this file, you can instruct `xstar' to use them
-in order to verify the integrity of the expanded file. The option `-x'
+ Additionally, if your 'tar' implementation has extracted the
+"extended headers" for this file, you can instruct 'xstar' to use them
+in order to verify the integrity of the expanded file. The option '-x'
sets the name of the extended header file to use. Continuing our
example:
'/home/gray/sparsefile'
Done
- An "extended header" is a special `tar' archive header that precedes
+ An "extended header" is a special 'tar' archive header that precedes
an archive member and contains a set of "variables", describing the
-member properties that cannot be stored in the standard `ustar' header.
+member properties that cannot be stored in the standard 'ustar' header.
While optional for expanding sparse version 1.0 members, the use of
extended headers is mandatory when expanding sparse members in older
sparse formats: v.0.0 and v.0.1 (The sparse formats are described in
detail in *note Sparse Formats::.) So, for these formats, the question
is: how to obtain extended headers from the archive?
- If you use a `tar' implementation that does not support PAX format,
+ If you use a 'tar' implementation that does not support PAX format,
extended headers for each member will be extracted as a separate file.
-If we represent the member name as `DIR/NAME', then the extended header
-file will be named `DIR/PaxHeaders.N/NAME', where N is an integer
+If we represent the member name as 'DIR/NAME', then the extended header
+file will be named 'DIR/PaxHeaders.N/NAME', where N is an integer
number.
- Things become more difficult if your `tar' implementation does
+ Things become more difficult if your 'tar' implementation does
support PAX headers, because in this case you will have to manually
extract the headers. We recommend the following algorithm:
- 1. Consult the documentation of your `tar' implementation for an
+ 1. Consult the documentation of your 'tar' implementation for an
option that prints "block numbers" along with the archive listing
- (analogous to GNU `tar''s `-R' option). For example, `star' has
- `-block-number'.
+ (analogous to GNU 'tar''s '-R' option). For example, 'star' has
+ '-block-number'.
- 2. Obtain verbose listing using the `block number' option, and find
+ 2. Obtain verbose listing using the 'block number' option, and find
block numbers of the sparse member in question and the member
- immediately following it. For example, running `star' on our
+ immediately following it. For example, running 'star' on our
archive we obtain:
$ star -t -v -block-number -f arc.tar
N = BS - BN - SIZE/512 - 2
This number gives the size of the extended header part in tar
- "blocks". In our example, this formula gives: `897 - 56 - 425984
- / 512 - 2 = 7'.
+ "blocks". In our example, this formula gives: '897 - 56 - 425984 /
+ 512 - 2 = 7'.
- 4. Use `dd' to extract the headers:
+ 4. Use 'dd' to extract the headers:
dd if=ARCHIVE of=HNAME bs=512 skip=BS count=N
(1) *Note PAX 1::.
- (2) Technically speaking, N is a "process ID" of the `tar' process
+ (2) Technically speaking, N is a "process ID" of the 'tar' process
which created the archive (*note PAX keywords::).
\1f
File: tar.info, Node: cpio, Prev: Portability, Up: Formats
-8.4 Comparison of `tar' and `cpio'
+8.4 Comparison of 'tar' and 'cpio'
==================================
_(This message will disappear, once this node revised.)_
-The `cpio' archive formats, like `tar', do have maximum file name
-lengths. The binary and old ASCII formats have a maximum file length
-of 256, and the new ASCII and CRC ASCII formats have a max file length
-of 1024. GNU `cpio' can read and write archives with arbitrary file
-name lengths, but other `cpio' implementations may crash unexplainedly
-trying to read them.
+ The 'cpio' archive formats, like 'tar', do have maximum file name
+lengths. The binary and old ASCII formats have a maximum file length of
+256, and the new ASCII and CRC ASCII formats have a max file length of
+1024. GNU 'cpio' can read and write archives with arbitrary file name
+lengths, but other 'cpio' implementations may crash unexplainedly trying
+to read them.
- `tar' handles symbolic links in the form in which it comes in BSD;
-`cpio' doesn't handle symbolic links in the form in which it comes in
+ 'tar' handles symbolic links in the form in which it comes in BSD;
+'cpio' doesn't handle symbolic links in the form in which it comes in
System V prior to SVR4, and some vendors may have added symlinks to
-their system without enhancing `cpio' to know about them. Others may
+their system without enhancing 'cpio' to know about them. Others may
have enhanced it in a way other than the way I did it at Sun, and which
-was adopted by AT&T (and which is, I think, also present in the `cpio'
+was adopted by AT&T (and which is, I think, also present in the 'cpio'
that Berkeley picked up from AT&T and put into a later BSD release--I
think I gave them my changes).
- (SVR4 does some funny stuff with `tar'; basically, its `cpio' can
-handle `tar' format input, and write it on output, and it probably
+ (SVR4 does some funny stuff with 'tar'; basically, its 'cpio' can
+handle 'tar' format input, and write it on output, and it probably
handles symbolic links. They may not have bothered doing anything to
-enhance `tar' as a result.)
+enhance 'tar' as a result.)
- `cpio' handles special files; traditional `tar' doesn't.
+ 'cpio' handles special files; traditional 'tar' doesn't.
- `tar' comes with V7, System III, System V, and BSD source; `cpio'
+ 'tar' comes with V7, System III, System V, and BSD source; 'cpio'
comes only with System III, System V, and later BSD (4.3-tahoe and
later).
- `tar''s way of handling multiple hard links to a file can handle
-file systems that support 32-bit i-numbers (e.g., the BSD file system);
-`cpio's way requires you to play some games (in its "binary" format,
+ 'tar''s way of handling multiple hard links to a file can handle file
+systems that support 32-bit i-numbers (e.g., the BSD file system);
+'cpio's way requires you to play some games (in its "binary" format,
i-numbers are only 16 bits, and in its "portable ASCII" format, they're
18 bits--it would have to play games with the "file system ID" field of
the header to make sure that the file system ID/i-number pairs of
-different files were always different), and I don't know which `cpio's,
-if any, play those games. Those that don't might get confused and
-think two files are the same file when they're not, and make hard links
+different files were always different), and I don't know which 'cpio's,
+if any, play those games. Those that don't might get confused and think
+two files are the same file when they're not, and make hard links
between them.
- `tar's way of handling multiple hard links to a file places only one
+ 'tar's way of handling multiple hard links to a file places only one
copy of the link on the tape, but the name attached to that copy is the
-_only_ one you can use to retrieve the file; `cpio's way puts one copy
+_only_ one you can use to retrieve the file; 'cpio's way puts one copy
for every link, but you can retrieve it using any of the names.
What type of check sum (if any) is used, and how is this
calculated.
- See the attached manual pages for `tar' and `cpio' format. `tar'
-uses a checksum which is the sum of all the bytes in the `tar' header
-for a file; `cpio' uses no checksum.
+ See the attached manual pages for 'tar' and 'cpio' format. 'tar'
+uses a checksum which is the sum of all the bytes in the 'tar' header
+for a file; 'cpio' uses no checksum.
- If anyone knows why `cpio' was made when `tar' was present at the
+ If anyone knows why 'cpio' was made when 'tar' was present at the
unix scene,
- It wasn't. `cpio' first showed up in PWB/UNIX 1.0; no
-generally-available version of UNIX had `tar' at the time. I don't
-know whether any version that was generally available _within AT&T_ had
-`tar', or, if so, whether the people within AT&T who did `cpio' knew
+ It wasn't. 'cpio' first showed up in PWB/UNIX 1.0; no
+generally-available version of UNIX had 'tar' at the time. I don't know
+whether any version that was generally available _within AT&T_ had
+'tar', or, if so, whether the people within AT&T who did 'cpio' knew
about it.
- On restore, if there is a corruption on a tape `tar' will stop at
-that point, while `cpio' will skip over it and try to restore the rest
+ On restore, if there is a corruption on a tape 'tar' will stop at
+that point, while 'cpio' will skip over it and try to restore the rest
of the files.
The main difference is just in the command syntax and header format.
- `tar' is a little more tape-oriented in that everything is blocked
-to start on a record boundary.
+ 'tar' is a little more tape-oriented in that everything is blocked to
+start on a record boundary.
Is there any differences between the ability to recover crashed
archives between the two of them. (Is there any chance of
recovering crashed archives at all.)
- Theoretically it should be easier under `tar' since the blocking
-lets you find a header with some variation of `dd skip=NN'. However,
-modern `cpio''s and variations have an option to just search for the
-next file header after an error with a reasonable chance of resyncing.
-However, lots of tape driver software won't allow you to continue past
-a media error which should be the only reason for getting out of sync
-unless a file changed sizes while you were writing the archive.
+ Theoretically it should be easier under 'tar' since the blocking lets
+you find a header with some variation of 'dd skip=NN'. However, modern
+'cpio''s and variations have an option to just search for the next file
+header after an error with a reasonable chance of resyncing. However,
+lots of tape driver software won't allow you to continue past a media
+error which should be the only reason for getting out of sync unless a
+file changed sizes while you were writing the archive.
- If anyone knows why `cpio' was made when `tar' was present at the
+ If anyone knows why 'cpio' was made when 'tar' was present at the
unix scene, please tell me about this too.
Probably because it is more media efficient (by not blocking
-everything and using only the space needed for the headers where `tar'
+everything and using only the space needed for the headers where 'tar'
always uses 512 bytes per file header) and it knows how to archive
special files.
You might want to look at the freely available alternatives. The
-major ones are `afio', GNU `tar', and `pax', each of which have their
+major ones are 'afio', GNU 'tar', and 'pax', each of which have their
own extensions with some backwards compatibility.
- Sparse files were `tar'red as sparse files (which you can easily
-test, because the resulting archive gets smaller, and GNU `cpio' can no
+ Sparse files were 'tar'red as sparse files (which you can easily
+test, because the resulting archive gets smaller, and GNU 'cpio' can no
longer read it).
\1f
_(This message will disappear, once this node revised.)_
-A few special cases about tape handling warrant more detailed
+ A few special cases about tape handling warrant more detailed
description. These special cases are discussed below.
- Many complexities surround the use of `tar' on tape drives. Since
+ Many complexities surround the use of 'tar' on tape drives. Since
the creation and manipulation of archives located on magnetic tape was
-the original purpose of `tar', it contains many features making such
+the original purpose of 'tar', it contains many features making such
manipulation easier.
Archives are usually written on dismountable media--tape cartridges,
physically smaller EXABYTE tape cartridge holds 2.3 gigabytes.
Magnetic media are re-usable--once the archive on a tape is no longer
-needed, the archive can be erased and the tape or disk used over.
-Media quality does deteriorate with use, however. Most tapes or disks
-should be discarded when they begin to produce data errors. EXABYTE
-tape cartridges should be discarded when they generate an "error count"
+needed, the archive can be erased and the tape or disk used over. Media
+quality does deteriorate with use, however. Most tapes or disks should
+be discarded when they begin to produce data errors. EXABYTE tape
+cartridges should be discarded when they generate an "error count"
(number of non-usable bits) of more than 10k.
Magnetic media are written and erased using magnetic fields, and
_(This message will disappear, once this node revised.)_
-`-f [HOSTNAME:]FILE'
-`--file=[HOSTNAME:]FILE'
+'-f [HOSTNAME:]FILE'
+'--file=[HOSTNAME:]FILE'
Use archive file or device FILE on HOSTNAME.
- This option is used to specify the file name of the archive `tar'
+ This option is used to specify the file name of the archive 'tar'
works on.
- If the file name is `-', `tar' reads the archive from standard input
+ If the file name is '-', 'tar' reads the archive from standard input
(when listing or extracting), or writes it to standard output (when
-creating). If the `-' file name is given when updating an archive,
-`tar' will read the original archive from its standard input, and will
+creating). If the '-' file name is given when updating an archive,
+'tar' will read the original archive from its standard input, and will
write the entire new archive to its standard output.
- If the file name contains a `:', it is interpreted as `hostname:file
-name'. If the HOSTNAME contains an "at" sign (`@'), it is treated as
-`user@hostname:file name'. In either case, `tar' will invoke the
-command `rsh' (or `remsh') to start up an `/usr/libexec/rmt' on the
+ If the file name contains a ':', it is interpreted as 'hostname:file
+name'. If the HOSTNAME contains an "at" sign ('@'), it is treated as
+'user@hostname:file name'. In either case, 'tar' will invoke the
+command 'rsh' (or 'remsh') to start up an '/usr/libexec/rmt' on the
remote machine. If you give an alternate login name, it will be given
-to the `rsh'. Naturally, the remote machine must have an executable
-`/usr/libexec/rmt'. This program is free software from the University
+to the 'rsh'. Naturally, the remote machine must have an executable
+'/usr/libexec/rmt'. This program is free software from the University
of California, and a copy of the source code can be found with the
-sources for `tar'; it's compiled and installed by default. The exact
+sources for 'tar'; it's compiled and installed by default. The exact
path to this utility is determined when configuring the package. It is
-`PREFIX/libexec/rmt', where PREFIX stands for your installation prefix.
+'PREFIX/libexec/rmt', where PREFIX stands for your installation prefix.
This location may also be overridden at runtime by using the
-`--rmt-command=COMMAND' option (*Note --rmt-command: Option Summary,
-for detailed description of this option. *Note Remote Tape Server::,
-for the description of `rmt' command).
+'--rmt-command=COMMAND' option (*Note --rmt-command: Option Summary, for
+detailed description of this option. *Note Remote Tape Server::, for
+the description of 'rmt' command).
- If this option is not given, but the environment variable `TAPE' is
-set, its value is used; otherwise, old versions of `tar' used a default
-archive name (which was picked when `tar' was compiled). The default
-is normally set up to be the "first" tape drive or other transportable
-I/O medium on the system.
+ If this option is not given, but the environment variable 'TAPE' is
+set, its value is used; otherwise, old versions of 'tar' used a default
+archive name (which was picked when 'tar' was compiled). The default is
+normally set up to be the "first" tape drive or other transportable I/O
+medium on the system.
- Starting with version 1.11.5, GNU `tar' uses standard input and
+ Starting with version 1.11.5, GNU 'tar' uses standard input and
standard output as the default device, and I will not try anymore
supporting automatic device detection at installation time. This was
failing really in too many cases, it was hopeless. This is now
-completely left to the installer to override standard input and
-standard output for default device, if this seems preferable. Further,
-I think _most_ actual usages of `tar' are done with pipes or disks, not
-really tapes, cartridges or diskettes.
+completely left to the installer to override standard input and standard
+output for default device, if this seems preferable. Further, I think
+_most_ actual usages of 'tar' are done with pipes or disks, not really
+tapes, cartridges or diskettes.
Some users think that using standard input and output is running
after trouble. This could lead to a nasty surprise on your screen if
you forget to specify an output file name--especially if you are going
through a network or terminal server capable of buffering large amounts
of output. We had so many bug reports in that area of configuring
-default tapes automatically, and so many contradicting requests, that
-we finally consider the problem to be portably intractable. We could
-of course use something like `/dev/tape' as a default, but this is
-_also_ running after various kind of trouble, going from hung processes
-to accidental destruction of real tapes. After having seen all this
-mess, using standard input and output as a default really sounds like
-the only clean choice left, and a very useful one too.
-
- GNU `tar' reads and writes archive in records, I suspect this is the
+default tapes automatically, and so many contradicting requests, that we
+finally consider the problem to be portably intractable. We could of
+course use something like '/dev/tape' as a default, but this is _also_
+running after various kind of trouble, going from hung processes to
+accidental destruction of real tapes. After having seen all this mess,
+using standard input and output as a default really sounds like the only
+clean choice left, and a very useful one too.
+
+ GNU 'tar' reads and writes archive in records, I suspect this is the
main reason why block devices are preferred over character devices.
Most probably, block devices are more efficient too. The installer
-could also check for `DEFTAPE' in `<sys/mtio.h>'.
+could also check for 'DEFTAPE' in '<sys/mtio.h>'.
-`--force-local'
+'--force-local'
Archive file is local even if it contains a colon.
-`--rsh-command=COMMAND'
- Use remote COMMAND instead of `rsh'. This option exists so that
- people who use something other than the standard `rsh' (e.g., a
- Kerberized `rsh') can access a remote device.
+'--rsh-command=COMMAND'
+ Use remote COMMAND instead of 'rsh'. This option exists so that
+ people who use something other than the standard 'rsh' (e.g., a
+ Kerberized 'rsh') can access a remote device.
When this command is not used, the shell command found when the
- `tar' program was installed is used instead. This is the first
- found of `/usr/ucb/rsh', `/usr/bin/remsh', `/usr/bin/rsh',
- `/usr/bsd/rsh' or `/usr/bin/nsh'. The installer may have
- overridden this by defining the environment variable `RSH' _at
+ 'tar' program was installed is used instead. This is the first
+ found of '/usr/ucb/rsh', '/usr/bin/remsh', '/usr/bin/rsh',
+ '/usr/bsd/rsh' or '/usr/bin/nsh'. The installer may have
+ overridden this by defining the environment variable 'RSH' _at
installation time_.
-`-[0-7][lmh]'
+'-[0-7][lmh]'
Specify drive and density.
-`-M'
-`--multi-volume'
+'-M'
+'--multi-volume'
Create/list/extract multi-volume archive.
- This option causes `tar' to write a "multi-volume" archive--one
+ This option causes 'tar' to write a "multi-volume" archive--one
that may be larger than will fit on the medium used to hold it.
*Note Multi-Volume Archives::.
-`-L NUM'
-`--tape-length=SIZE[SUF]'
- Change tape after writing SIZE units of data. Unless SUF is
- given, SIZE is treated as kilobytes, i.e. `SIZE x 1024' bytes.
- The following suffixes alter this behavior:
-
- Suffix Units Byte Equivalent
- --------------------------------------------------------
- b Blocks SIZE x 512
- B Kilobytes SIZE x 1024
- c Bytes SIZE
- G Gigabytes SIZE x 1024^3
- K Kilobytes SIZE x 1024
- k Kilobytes SIZE x 1024
- M Megabytes SIZE x 1024^2
- P Petabytes SIZE x 1024^5
- T Terabytes SIZE x 1024^4
- w Words SIZE x 2
+'-L NUM'
+'--tape-length=SIZE[SUF]'
+ Change tape after writing SIZE units of data. Unless SUF is given,
+ SIZE is treated as kilobytes, i.e. 'SIZE x 1024' bytes. The
+ following suffixes alter this behavior:
+
+ Suffix Units Byte Equivalent
+ -------------------------------------------------------------
+ b Blocks SIZE x 512
+ B Kilobytes SIZE x 1024
+ c Bytes SIZE
+ G Gigabytes SIZE x 1024^3
+ K Kilobytes SIZE x 1024
+ k Kilobytes SIZE x 1024
+ M Megabytes SIZE x 1024^2
+ P Petabytes SIZE x 1024^5
+ T Terabytes SIZE x 1024^4
+ w Words SIZE x 2
Table 9.1: Size Suffixes
- This option might be useful when your tape drivers do not
- properly detect end of physical tapes. By being slightly
- conservative on the maximum tape length, you might avoid the
- problem entirely.
+ This option might be useful when your tape drivers do not properly
+ detect end of physical tapes. By being slightly conservative on
+ the maximum tape length, you might avoid the problem entirely.
- `-F COMMAND'
- `--info-script=COMMAND'
- `--new-volume-script=COMMAND'
- Execute COMMAND at end of each tape. This implies
- `--multi-volume' (`-M'). *Note info-script::, for a detailed
- description of this option.
+'-F COMMAND'
+'--info-script=COMMAND'
+'--new-volume-script=COMMAND'
+ Execute COMMAND at end of each tape. This implies '--multi-volume'
+ ('-M'). *Note info-script::, for a detailed description of this
+ option.
\1f
File: tar.info, Node: Remote Tape Server, Next: Common Problems and Solutions, Prev: Device, Up: Media
9.2 Remote Tape Server
======================
-In order to access the tape drive on a remote machine, `tar' uses the
+In order to access the tape drive on a remote machine, 'tar' uses the
remote tape server written at the University of California at Berkeley.
-The remote tape server must be installed as `PREFIX/libexec/rmt' on any
-machine whose tape drive you want to use. `tar' calls `rmt' by running
-an `rsh' or `remsh' to the remote machine, optionally using a different
+The remote tape server must be installed as 'PREFIX/libexec/rmt' on any
+machine whose tape drive you want to use. 'tar' calls 'rmt' by running
+an 'rsh' or 'remsh' to the remote machine, optionally using a different
login name if one is supplied.
A copy of the source for the remote tape server is provided. Its
source code can be freely distributed. It is compiled and installed by
default.
- Unless you use the `--absolute-names' (`-P') option, GNU `tar' will
+ Unless you use the '--absolute-names' ('-P') option, GNU 'tar' will
not allow you to create an archive that contains absolute file names (a
-file name beginning with `/'.) If you try, `tar' will automatically
-remove the leading `/' from the file names it stores in the archive.
-It will also type a warning message telling you what it is doing.
+file name beginning with '/'). If you try, 'tar' will automatically
+remove the leading '/' from the file names it stores in the archive. It
+will also type a warning message telling you what it is doing.
- When reading an archive that was created with a different `tar'
-program, GNU `tar' automatically extracts entries in the archive which
+ When reading an archive that was created with a different 'tar'
+program, GNU 'tar' automatically extracts entries in the archive which
have absolute file names as if the file names were not absolute. This
-is an important feature. A visitor here once gave a `tar' tape to an
-operator to restore; the operator used Sun `tar' instead of GNU `tar',
-and the result was that it replaced large portions of our `/bin' and
+is an important feature. A visitor here once gave a 'tar' tape to an
+operator to restore; the operator used Sun 'tar' instead of GNU 'tar',
+and the result was that it replaced large portions of our '/bin' and
friends with versions from the tape; needless to say, we were unhappy
about having to recover the file system from backup tapes.
- For example, if the archive contained a file `/usr/bin/computoy',
-GNU `tar' would extract the file to `usr/bin/computoy', relative to the
+ For example, if the archive contained a file '/usr/bin/computoy', GNU
+'tar' would extract the file to 'usr/bin/computoy', relative to the
current directory. If you want to extract the files in an archive to
the same absolute names that they had when the archive was created, you
-should do a `cd /' before extracting the files from the archive, or you
-should either use the `--absolute-names' option, or use the command
-`tar -C / ...'.
+should do a 'cd /' before extracting the files from the archive, or you
+should either use the '--absolute-names' option, or use the command 'tar
+-C / ...'.
- Some versions of Unix (Ultrix 3.1 is known to have this problem),
-can claim that a short write near the end of a tape succeeded, when it
+ Some versions of Unix (Ultrix 3.1 is known to have this problem), can
+claim that a short write near the end of a tape succeeded, when it
actually failed. This will result in the -M option not working
correctly. The best workaround at the moment is to use a significantly
larger blocking factor than the default 20.
- In order to update an archive, `tar' must be able to backspace the
+ In order to update an archive, 'tar' must be able to backspace the
archive in order to reread or rewrite a record that was just read (or
written). This is currently possible only on two kinds of files: normal
-disk files (or any other file that can be backspaced with `lseek'), and
+disk files (or any other file that can be backspaced with 'lseek'), and
industry-standard 9-track magnetic tape (or any other kind of tape that
-can be backspaced with the `MTIOCTOP' `ioctl').
+can be backspaced with the 'MTIOCTOP' 'ioctl').
- This means that the `--append', `--concatenate', and `--delete'
+ This means that the '--append', '--concatenate', and '--delete'
commands will not work on any other kind of file. Some media simply
cannot be backspaced, which means these commands and options will never
be able to work on them. These non-backspacing media include pipes and
cartridge tape drives.
- Some other media can be backspaced, and `tar' will work on them once
-`tar' is modified to do so.
+ Some other media can be backspaced, and 'tar' will work on them once
+'tar' is modified to do so.
- Archives created with the `--multi-volume', `--label', and
-`--incremental' (`-G') options may not be readable by other version of
-`tar'. In particular, restoring a file that was split over a volume
-boundary will require some careful work with `dd', if it can be done at
-all. Other versions of `tar' may also create an empty file whose name
-is that of the volume header. Some versions of `tar' may create normal
-files instead of directories archived with the `--incremental' (`-G')
+ Archives created with the '--multi-volume', '--label', and
+'--incremental' ('-G') options may not be readable by other version of
+'tar'. In particular, restoring a file that was split over a volume
+boundary will require some careful work with 'dd', if it can be done at
+all. Other versions of 'tar' may also create an empty file whose name
+is that of the volume header. Some versions of 'tar' may create normal
+files instead of directories archived with the '--incremental' ('-G')
option.
\1f
no such file or directory
not owner
-errors from `tar':
+errors from 'tar':
directory checksum error
header format error
paragraphs, as the remainder of this manual uses those two terms in a
quite consistent way.
- John Gilmore, the writer of the public domain `tar' from which GNU
-`tar' was originally derived, wrote (June 1995):
+ John Gilmore, the writer of the public domain 'tar' from which GNU
+'tar' was originally derived, wrote (June 1995):
The nomenclature of tape drives comes from IBM, where I believe
they were invented for the IBM 650 or so. On IBM mainframes, what
is recorded on tape are tape blocks. The logical organization of
data is into records. There are various ways of putting records
- into blocks, including `F' (fixed sized records), `V' (variable
- sized records), `FB' (fixed blocked: fixed size records, N to a
- block), `VB' (variable size records, N to a block), `VSB'
- (variable spanned blocked: variable sized records that can occupy
- more than one block), etc. The `JCL' `DD RECFORM=' parameter
- specified this to the operating system.
-
- The Unix man page on `tar' was totally confused about this. When
- I wrote `PD TAR', I used the historically correct terminology
- (`tar' writes data records, which are grouped into blocks). It
- appears that the bogus terminology made it into POSIX (no surprise
- here), and now Franc,ois has migrated that terminology back into
- the source code too.
-
- The term "physical block" means the basic transfer chunk from or to
-a device, after which reading or writing may stop without anything
-being lost. In this manual, the term "block" usually refers to a disk
+ into blocks, including 'F' (fixed sized records), 'V' (variable
+ sized records), 'FB' (fixed blocked: fixed size records, N to a
+ block), 'VB' (variable size records, N to a block), 'VSB' (variable
+ spanned blocked: variable sized records that can occupy more than
+ one block), etc. The 'JCL' 'DD RECFORM=' parameter specified this
+ to the operating system.
+
+ The Unix man page on 'tar' was totally confused about this. When I
+ wrote 'PD TAR', I used the historically correct terminology ('tar'
+ writes data records, which are grouped into blocks). It appears
+ that the bogus terminology made it into POSIX (no surprise here),
+ and now Franc,ois has migrated that terminology back into the
+ source code too.
+
+ The term "physical block" means the basic transfer chunk from or to a
+device, after which reading or writing may stop without anything being
+lost. In this manual, the term "block" usually refers to a disk
physical block, _assuming_ that each disk block is 512 bytes in length.
It is true that some disk devices have different physical blocks, but
-`tar' ignore these differences in its own format, which is meant to be
-portable, so a `tar' block is always 512 bytes in length, and "block"
-always mean a `tar' block. The term "logical block" often represents
+'tar' ignore these differences in its own format, which is meant to be
+portable, so a 'tar' block is always 512 bytes in length, and "block"
+always mean a 'tar' block. The term "logical block" often represents
the basic chunk of allocation of many disk blocks as a single entity,
which the operating system treats somewhat atomically; this concept is
-only barely used in GNU `tar'.
+only barely used in GNU 'tar'.
The term "physical record" is another way to speak of a physical
block, those two terms are somewhat interchangeable. In this manual,
the term "record" usually refers to a tape physical block, _assuming_
-that the `tar' archive is kept on magnetic tape. It is true that
-archives may be put on disk or used with pipes, but nevertheless, `tar'
-tries to read and write the archive one "record" at a time, whatever
-the medium in use. One record is made up of an integral number of
-blocks, and this operation of putting many disk blocks into a single
-tape block is called "reblocking", or more simply, "blocking". The
-term "logical record" refers to the logical organization of many
-characters into something meaningful to the application. The term
-"unit record" describes a small set of characters which are transmitted
-whole to or by the application, and often refers to a line of text.
-Those two last terms are unrelated to what we call a "record" in GNU
-`tar'.
-
- When writing to tapes, `tar' writes the contents of the archive in
+that the 'tar' archive is kept on magnetic tape. It is true that
+archives may be put on disk or used with pipes, but nevertheless, 'tar'
+tries to read and write the archive one "record" at a time, whatever the
+medium in use. One record is made up of an integral number of blocks,
+and this operation of putting many disk blocks into a single tape block
+is called "reblocking", or more simply, "blocking". The term "logical
+record" refers to the logical organization of many characters into
+something meaningful to the application. The term "unit record"
+describes a small set of characters which are transmitted whole to or by
+the application, and often refers to a line of text. Those two last
+terms are unrelated to what we call a "record" in GNU 'tar'.
+
+ When writing to tapes, 'tar' writes the contents of the archive in
chunks known as "records". To change the default blocking factor, use
-the `--blocking-factor=512-SIZE' (`-b 512-SIZE') option. Each record
-will then be composed of 512-SIZE blocks. (Each `tar' block is 512
+the '--blocking-factor=512-SIZE' ('-b 512-SIZE') option. Each record
+will then be composed of 512-SIZE blocks. (Each 'tar' block is 512
bytes. *Note Standard::.) Each file written to the archive uses at
least one full record. As a result, using a larger record size can
result in more wasted space for small files. On the other hand, a
honor the blocking), but not as dramatically as on tape drives that
honor blocking.
- When reading an archive, `tar' can usually figure out the record
-size on itself. When this is the case, and a non-standard record size
-was used when the archive was created, `tar' will print a message about
-a non-standard blocking factor, and then operate normally(1). On some
-tape devices, however, `tar' cannot figure out the record size itself.
+ When reading an archive, 'tar' can usually figure out the record size
+on itself. When this is the case, and a non-standard record size was
+used when the archive was created, 'tar' will print a message about a
+non-standard blocking factor, and then operate normally(1). On some
+tape devices, however, 'tar' cannot figure out the record size itself.
On most of those, you can specify a blocking factor (with
-`--blocking-factor') larger than the actual blocking factor, and then
-use the `--read-full-records' (`-B') option. (If you specify a
-blocking factor with `--blocking-factor' and don't use the
-`--read-full-records' option, then `tar' will not attempt to figure out
-the recording size itself.) On some devices, you must always specify
-the record size exactly with `--blocking-factor' when reading, because
-`tar' cannot figure it out. In any case, use `--list' (`-t') before
-doing any extractions to see whether `tar' is reading the archive
-correctly.
-
- `tar' blocks are all fixed size (512 bytes), and its scheme for
-putting them into records is to put a whole number of them (one or
-more) into each record. `tar' records are all the same size; at the
-end of the file there's a block containing all zeros, which is how you
-tell that the remainder of the last record(s) are garbage.
-
- In a standard `tar' file (no options), the block size is 512 and the
+'--blocking-factor') larger than the actual blocking factor, and then
+use the '--read-full-records' ('-B') option. (If you specify a blocking
+factor with '--blocking-factor' and don't use the '--read-full-records'
+option, then 'tar' will not attempt to figure out the recording size
+itself.) On some devices, you must always specify the record size
+exactly with '--blocking-factor' when reading, because 'tar' cannot
+figure it out. In any case, use '--list' ('-t') before doing any
+extractions to see whether 'tar' is reading the archive correctly.
+
+ 'tar' blocks are all fixed size (512 bytes), and its scheme for
+putting them into records is to put a whole number of them (one or more)
+into each record. 'tar' records are all the same size; at the end of
+the file there's a block containing all zeros, which is how you tell
+that the remainder of the last record(s) are garbage.
+
+ In a standard 'tar' file (no options), the block size is 512 and the
record size is 10240, for a blocking factor of 20. What the
-`--blocking-factor' option does is sets the blocking factor, changing
+'--blocking-factor' option does is sets the blocking factor, changing
the record size while leaving the block size at 512 bytes. 20 was fine
for ancient 800 or 1600 bpi reel-to-reel tape drives; most tape drives
these days prefer much bigger records in order to stream and not waste
tape. When writing tapes for myself, some tend to use a factor of the
order of 2048, say, giving a record size of around one megabyte.
- If you use a blocking factor larger than 20, older `tar' programs
+ If you use a blocking factor larger than 20, older 'tar' programs
might not be able to read the archive, so we recommend this as a limit
-to use in practice. GNU `tar', however, will support arbitrarily large
+to use in practice. GNU 'tar', however, will support arbitrarily large
record sizes, limited only by the amount of virtual memory or the
physical characteristics of the tape device.
---------- Footnotes ----------
(1) If this message is not needed, you can turn it off using the
-`--warning=no-record-size' option.
+'--warning=no-record-size' option.
\1f
File: tar.info, Node: Format Variations, Next: Blocking Factor, Up: Blocking
_(This message will disappear, once this node revised.)_
-Format parameters specify how an archive is written on the archive
+ Format parameters specify how an archive is written on the archive
media. The best choice of format parameters will vary depending on the
type and number of files being archived, and on the media used to store
the archive.
To specify format parameters when accessing or creating an archive,
you can use the options described in the following sections. If you do
-not specify any format parameters, `tar' uses default parameters. You
+not specify any format parameters, 'tar' uses default parameters. You
cannot modify a compressed archive. If you create an archive with the
-`--blocking-factor' option specified (*note Blocking Factor::), you
-must specify that blocking-factor when operating on the archive. *Note
+'--blocking-factor' option specified (*note Blocking Factor::), you must
+specify that blocking-factor when operating on the archive. *Note
Formats::, for other examples of format parameter considerations.
\1f
_(This message will disappear, once this node revised.)_
-The data in an archive is grouped into blocks, which are 512 bytes.
+ The data in an archive is grouped into blocks, which are 512 bytes.
Blocks are read and written in whole number multiples called "records".
-The number of blocks in a record (i.e., the size of a record in units
-of 512 bytes) is called the "blocking factor". The
-`--blocking-factor=512-SIZE' (`-b 512-SIZE') option specifies the
-blocking factor of an archive. The default blocking factor is
-typically 20 (i.e., 10240 bytes), but can be specified at installation.
-To find out the blocking factor of an existing archive, use `tar --list
+The number of blocks in a record (i.e., the size of a record in units of
+512 bytes) is called the "blocking factor". The
+'--blocking-factor=512-SIZE' ('-b 512-SIZE') option specifies the
+blocking factor of an archive. The default blocking factor is typically
+20 (i.e., 10240 bytes), but can be specified at installation. To find
+out the blocking factor of an existing archive, use 'tar --list
--file=ARCHIVE-NAME'. This may not work on some devices.
Records are separated by gaps, which waste space on the archive
media. If you are archiving on magnetic tape, using a larger blocking
factor (and therefore larger records) provides faster throughput and
allows you to fit more data on a tape (because there are fewer gaps).
-If you are archiving on cartridge, a very large blocking factor (say
-126 or more) greatly increases performance. A smaller blocking factor,
-on the other hand, may be useful when archiving small files, to avoid
-archiving lots of nulls as `tar' fills out the archive to the end of
-the record. In general, the ideal record size depends on the size of
-the inter-record gaps on the tape you are using, and the average size
-of the files you are archiving. *Note create::, for information on
-writing archives.
+If you are archiving on cartridge, a very large blocking factor (say 126
+or more) greatly increases performance. A smaller blocking factor, on
+the other hand, may be useful when archiving small files, to avoid
+archiving lots of nulls as 'tar' fills out the archive to the end of the
+record. In general, the ideal record size depends on the size of the
+inter-record gaps on the tape you are using, and the average size of the
+files you are archiving. *Note create::, for information on writing
+archives.
Archives with blocking factors larger than 20 cannot be read by very
-old versions of `tar', or by some newer versions of `tar' running on
-old machines with small address spaces. With GNU `tar', the blocking
-factor of an archive is limited only by the maximum record size of the
-device containing the archive, or by the amount of available virtual
-memory.
+old versions of 'tar', or by some newer versions of 'tar' running on old
+machines with small address spaces. With GNU 'tar', the blocking factor
+of an archive is limited only by the maximum record size of the device
+containing the archive, or by the amount of available virtual memory.
Also, on some systems, not using adequate blocking factors, as
sometimes imposed by the device drivers, may yield unexpected
Cannot write to /dev/dlt: Invalid argument
-In such cases, it sometimes happen that the `tar' bundled by the system
-is aware of block size idiosyncrasies, while GNU `tar' requires an
+In such cases, it sometimes happen that the 'tar' bundled by the system
+is aware of block size idiosyncrasies, while GNU 'tar' requires an
explicit specification for the block size, which it cannot guess. This
-yields some people to consider GNU `tar' is misbehaving, because by
-comparison, `the bundle `tar' works OK'. Adding `-b 256', for example,
+yields some people to consider GNU 'tar' is misbehaving, because by
+comparison, 'the bundle 'tar' works OK'. Adding '-b 256', for example,
might resolve the problem.
If you use a non-default blocking factor when you create an archive,
you must specify the same blocking factor when you modify that archive.
Some archive devices will also require you to specify the blocking
factor when reading that archive, however this is not typically the
-case. Usually, you can use `--list' (`-t') without specifying a
-blocking factor--`tar' reports a non-default record size and then lists
+case. Usually, you can use '--list' ('-t') without specifying a
+blocking factor--'tar' reports a non-default record size and then lists
the archive members as it would normally. To extract files from an
archive with a non-standard blocking factor (particularly if you're not
sure what the blocking factor is), you can usually use the
-`--read-full-records' (`-B') option while specifying a blocking factor
-larger then the blocking factor of the archive (i.e., `tar --extract
+'--read-full-records' ('-B') option while specifying a blocking factor
+larger then the blocking factor of the archive (i.e., 'tar --extract
--read-full-records --blocking-factor=300'). *Note list::, for more
-information on the `--list' (`-t') operation. *Note Reading::, for a
+information on the '--list' ('-t') operation. *Note Reading::, for a
more detailed explanation of that option.
-`--blocking-factor=NUMBER'
-`-b NUMBER'
+'--blocking-factor=NUMBER'
+'-b NUMBER'
Specifies the blocking factor of an archive. Can be used with any
- operation, but is usually not necessary with `--list' (`-t').
+ operation, but is usually not necessary with '--list' ('-t').
Device blocking
-`-b BLOCKS'
-`--blocking-factor=BLOCKS'
+'-b BLOCKS'
+'--blocking-factor=BLOCKS'
Set record size to BLOCKS*512 bytes.
This option is used to specify a "blocking factor" for the archive.
- When reading or writing the archive, `tar', will do reads and
+ When reading or writing the archive, 'tar', will do reads and
writes of the archive in records of BLOCK*512 bytes. This is true
even when the archive is compressed. Some devices requires that
- all write operations be a multiple of a certain size, and so, `tar'
+ all write operations be a multiple of a certain size, and so, 'tar'
pads the archive out to the next record boundary.
- The default blocking factor is set when `tar' is compiled, and is
+ The default blocking factor is set when 'tar' is compiled, and is
typically 20. Blocking factors larger than 20 cannot be read by
- very old versions of `tar', or by some newer versions of `tar'
+ very old versions of 'tar', or by some newer versions of 'tar'
running on old machines with small address spaces.
With a magnetic tape, larger records give faster throughput and fit
Apparently, Exabyte drives have a physical block size of 8K bytes.
If we choose our blocksize as a multiple of 8k bytes, then the
- problem seems to disappear. Id est, we are using block size of
- 112 right now, and we haven't had the problem since we switched...
+ problem seems to disappear. Id est, we are using block size of 112
+ right now, and we haven't had the problem since we switched...
- With GNU `tar' the blocking factor is limited only by the maximum
+ With GNU 'tar' the blocking factor is limited only by the maximum
record size of the device containing the archive, or by the amount
of available virtual memory.
case which often occurs in practice, but which requires all the
following conditions to be simultaneously true:
* the archive is subject to a compression option,
-
* the archive is not handled through standard input or output,
nor redirected nor piped,
-
* the archive is directly handled to a local disk, instead of
any special device,
-
- * `--blocking-factor' is not explicitly specified on the `tar'
+ * '--blocking-factor' is not explicitly specified on the 'tar'
invocation.
If the output goes directly to a local disk, and not through
Otherwise, reblocking occurs. Here are a few other remarks on this
topic:
- * `gzip' will complain about trailing garbage if asked to
- uncompress a compressed archive on tape, there is an option
- to turn the message off, but it breaks the regularity of
- simply having to use `PROG -d' for decompression. It would
- be nice if gzip was silently ignoring any number of trailing
- zeros. I'll ask Jean-loup Gailly, by sending a copy of this
- message to him.
+ * 'gzip' will complain about trailing garbage if asked to
+ uncompress a compressed archive on tape, there is an option to
+ turn the message off, but it breaks the regularity of simply
+ having to use 'PROG -d' for decompression. It would be nice
+ if gzip was silently ignoring any number of trailing zeros.
+ I'll ask Jean-loup Gailly, by sending a copy of this message
+ to him.
- * `compress' does not show this problem, but as Jean-loup
- pointed out to Michael, `compress -d' silently adds garbage
+ * 'compress' does not show this problem, but as Jean-loup
+ pointed out to Michael, 'compress -d' silently adds garbage
after the result of decompression, which tar ignores because
it already recognized its end-of-file indicator. So this bug
may be safely ignored.
- * `gzip -d -q' will be silent about the trailing zeros indeed,
- but will still return an exit status of 2 which tar reports
- in turn. `tar' might ignore the exit status returned, but I
- hate doing that, as it weakens the protection `tar' offers
- users against other possible problems at decompression time.
- If `gzip' was silently skipping trailing zeros _and_ also
+ * 'gzip -d -q' will be silent about the trailing zeros indeed,
+ but will still return an exit status of 2 which tar reports in
+ turn. 'tar' might ignore the exit status returned, but I hate
+ doing that, as it weakens the protection 'tar' offers users
+ against other possible problems at decompression time. If
+ 'gzip' was silently skipping trailing zeros _and_ also
avoiding setting the exit status in this innocuous case, that
would solve this situation.
- * `tar' should become more solid at not stopping to read a pipe
+ * 'tar' should become more solid at not stopping to read a pipe
at the first null block encountered. This inelegantly breaks
- the pipe. `tar' should rather drain the pipe out before
+ the pipe. 'tar' should rather drain the pipe out before
exiting itself.
-`-i'
-`--ignore-zeros'
+'-i'
+'--ignore-zeros'
Ignore blocks of zeros in archive (means EOF).
- The `--ignore-zeros' (`-i') option causes `tar' to ignore blocks
- of zeros in the archive. Normally a block of zeros indicates the
- end of the archive, but when reading a damaged archive, or one
- which was created by concatenating several archives together, this
- option allows `tar' to read the entire archive. This option is
- not on by default because many versions of `tar' write garbage
- after the zeroed blocks.
+ The '--ignore-zeros' ('-i') option causes 'tar' to ignore blocks of
+ zeros in the archive. Normally a block of zeros indicates the end
+ of the archive, but when reading a damaged archive, or one which
+ was created by concatenating several archives together, this option
+ allows 'tar' to read the entire archive. This option is not on by
+ default because many versions of 'tar' write garbage after the
+ zeroed blocks.
- Note that this option causes `tar' to read to the end of the
+ Note that this option causes 'tar' to read to the end of the
archive file, which may sometimes avoid problems when multiple
files are stored on a single physical tape.
-`-B'
-`--read-full-records'
+'-B'
+'--read-full-records'
Reblock as we read (for reading 4.2BSD pipes).
- If `--read-full-records' is used, `tar' will not panic if an
+ If '--read-full-records' is used, 'tar' will not panic if an
attempt to read a record from the archive does not return a full
- record. Instead, `tar' will keep reading until it has obtained a
+ record. Instead, 'tar' will keep reading until it has obtained a
full record.
- This option is turned on by default when `tar' is reading an
+ This option is turned on by default when 'tar' is reading an
archive from standard input, or from a remote machine. This is
because on BSD Unix systems, a read of a pipe will return however
- much happens to be in the pipe, even if it is less than `tar'
- requested. If this option was not used, `tar' would fail as soon
+ much happens to be in the pipe, even if it is less than 'tar'
+ requested. If this option was not used, 'tar' would fail as soon
as it read an incomplete record from the pipe.
This option is also useful with the commands for updating an
archive.
-
Tape blocking
When handling various tapes or cartridges, you have to take care of
information on it, used for decelerating the tape to a full stop, and
for later regaining the reading or writing speed. When the tape driver
starts reading a record, the record has to be read whole without
-stopping, as a tape gap is needed to stop the tape motion without
-losing information.
+stopping, as a tape gap is needed to stop the tape motion without losing
+information.
Using higher blocking (putting more disk blocks per tape block) will
use the tape more efficiently as there will be less tape gaps. But
reading such tapes may be more difficult for the system, as more memory
-will be required to receive at once the whole record. Further, if
-there is a reading error on a huge record, this is less likely that the
-system will succeed in recovering the information. So, blocking should
-not be too low, nor it should be too high. `tar' uses by default a
-blocking of 20 for historical reasons, and it does not really matter
-when reading or writing to disk. Current tape technology would easily
-accommodate higher blockings. Sun recommends a blocking of 126 for
-Exabytes and 96 for DATs. We were told that for some DLT drives, the
-blocking should be a multiple of 4Kb, preferably 64Kb (`-b 128') or 256
-for decent performance. Other manufacturers may use different
-recommendations for the same tapes. This might also depends of the
-buffering techniques used inside modern tape controllers. Some imposes
-a minimum blocking, or a maximum blocking. Others request blocking to
-be some exponent of two.
+will be required to receive at once the whole record. Further, if there
+is a reading error on a huge record, this is less likely that the system
+will succeed in recovering the information. So, blocking should not be
+too low, nor it should be too high. 'tar' uses by default a blocking of
+20 for historical reasons, and it does not really matter when reading or
+writing to disk. Current tape technology would easily accommodate
+higher blockings. Sun recommends a blocking of 126 for Exabytes and 96
+for DATs. We were told that for some DLT drives, the blocking should be
+a multiple of 4Kb, preferably 64Kb ('-b 128') or 256 for decent
+performance. Other manufacturers may use different recommendations for
+the same tapes. This might also depends of the buffering techniques
+used inside modern tape controllers. Some imposes a minimum blocking,
+or a maximum blocking. Others request blocking to be some exponent of
+two.
So, there is no fixed rule for blocking. But blocking at read time
should ideally be the same as blocking used at write time. At one place
drive unit that will be used to create the archives) sometimes lowers
the error rates observed at rewriting time.
- I might also use `--number-blocks' instead of `--block-number', so
-`--block' will then expand to `--blocking-factor' unambiguously.
+ I might also use '--number-blocks' instead of '--block-number', so
+'--block' will then expand to '--blocking-factor' unambiguously.
\1f
File: tar.info, Node: Many, Next: Using Multiple Tapes, Prev: Blocking, Up: Media
9.5 Many Archives on One Tape
=============================
-Most tape devices have two entries in the `/dev' directory, or entries
+Most tape devices have two entries in the '/dev' directory, or entries
that come in pairs, which differ only in the minor number for this
-device. Let's take for example `/dev/tape', which often points to the
+device. Let's take for example '/dev/tape', which often points to the
only or usual tape device of a given system. There might be a
-corresponding `/dev/nrtape' or `/dev/ntape'. The simpler name is the
-_rewinding_ version of the device, while the name having `nr' in it is
+corresponding '/dev/nrtape' or '/dev/ntape'. The simpler name is the
+_rewinding_ version of the device, while the name having 'nr' in it is
the _no rewinding_ version of the same device.
A rewinding tape device will bring back the tape to its beginning
-point automatically when this device is opened or closed. Since `tar'
+point automatically when this device is opened or closed. Since 'tar'
opens the archive file before using it and closes it afterwards, this
means that a simple:
$ tar cf /dev/tape DIRECTORY
will reposition the tape to its beginning both prior and after saving
-DIRECTORY contents to it, thus erasing prior tape contents and making
-it so that any subsequent write operation will destroy what has just
-been saved.
+DIRECTORY contents to it, thus erasing prior tape contents and making it
+so that any subsequent write operation will destroy what has just been
+saved.
So, a rewinding device is normally meant to hold one and only one
-file. If you want to put more than one `tar' archive on a given tape,
+file. If you want to put more than one 'tar' archive on a given tape,
you will need to avoid using the rewinding version of the tape device.
-You will also have to pay special attention to tape positioning.
-Errors in positioning may overwrite the valuable data already on your
-tape. Many people, burnt by past experiences, will only use rewinding
-devices and limit themselves to one file per tape, precisely to avoid
-the risk of such errors. Be fully aware that writing at the wrong
-position on a tape loses all information past this point and most
-probably until the end of the tape, and this destroyed information
-_cannot_ be recovered.
+You will also have to pay special attention to tape positioning. Errors
+in positioning may overwrite the valuable data already on your tape.
+Many people, burnt by past experiences, will only use rewinding devices
+and limit themselves to one file per tape, precisely to avoid the risk
+of such errors. Be fully aware that writing at the wrong position on a
+tape loses all information past this point and most probably until the
+end of the tape, and this destroyed information _cannot_ be recovered.
To save DIRECTORY-1 as a first archive at the beginning of a tape,
and leave that tape ready for a second archive, you should use:
$ mt -f /dev/nrtape rewind
$ tar cf /dev/nrtape DIRECTORY-1
- "Tape marks" are special magnetic patterns written on the tape
-media, which are later recognizable by the reading hardware. These
-marks are used after each file, when there are many on a single tape.
-An empty file (that is to say, two tape marks in a row) signal the
-logical end of the tape, after which no file exist. Usually,
-non-rewinding tape device drivers will react to the close request issued
-by `tar' by first writing two tape marks after your archive, and by
-backspacing over one of these. So, if you remove the tape at that time
-from the tape drive, it is properly terminated. But if you write
-another file at the current position, the second tape mark will be
-erased by the new information, leaving only one tape mark between files.
+ "Tape marks" are special magnetic patterns written on the tape media,
+which are later recognizable by the reading hardware. These marks are
+used after each file, when there are many on a single tape. An empty
+file (that is to say, two tape marks in a row) signal the logical end of
+the tape, after which no file exist. Usually, non-rewinding tape device
+drivers will react to the close request issued by 'tar' by first writing
+two tape marks after your archive, and by backspacing over one of these.
+So, if you remove the tape at that time from the tape drive, it is
+properly terminated. But if you write another file at the current
+position, the second tape mark will be erased by the new information,
+leaving only one tape mark between files.
So, you may now save DIRECTORY-2 as a second archive after the first
on the same tape by issuing the command:
* Menu:
* Tape Positioning:: Tape Positions and Tape Marks
-* mt:: The `mt' Utility
+* mt:: The 'mt' Utility
\1f
File: tar.info, Node: Tape Positioning, Next: mt, Up: Many
_(This message will disappear, once this node revised.)_
-Just as archives can store more than one file from the file system,
+ Just as archives can store more than one file from the file system,
tapes can store more than one archive file. To keep track of where
archive files (or any other type of file stored on tape) begin and end,
tape archive devices write magnetic "tape marks" on the archive media.
-Tape drives write one tape mark between files, two at the end of all
-the file entries.
+Tape drives write one tape mark between files, two at the end of all the
+file entries.
If you think of data as a series of records "rrrr"'s, and tape marks
as "*"'s, a tape might look like the following:
Tape devices read and write tapes using a read/write "tape head"--a
physical part of the device which can only access one point on the tape
-at a time. When you use `tar' to read or write archive data from a
-tape device, the device will begin reading or writing from wherever on
-the tape the tape head happens to be, regardless of which archive or
-what part of the archive the tape head is on. Before writing an
-archive, you should make sure that no data on the tape will be
-overwritten (unless it is no longer needed). Before reading an
-archive, you should make sure the tape head is at the beginning of the
-archive you want to read. You can do it manually via `mt' utility
-(*note mt::). The `restore' script does that automatically (*note
-Scripted Restoration::).
+at a time. When you use 'tar' to read or write archive data from a tape
+device, the device will begin reading or writing from wherever on the
+tape the tape head happens to be, regardless of which archive or what
+part of the archive the tape head is on. Before writing an archive, you
+should make sure that no data on the tape will be overwritten (unless it
+is no longer needed). Before reading an archive, you should make sure
+the tape head is at the beginning of the archive you want to read. You
+can do it manually via 'mt' utility (*note mt::). The 'restore' script
+does that automatically (*note Scripted Restoration::).
If you want to add new archive file entries to a tape, you should
-advance the tape to the end of the existing file entries, backspace
-over the last tape mark, and write the new archive file. If you were
-to add two archives to the example above, the tape might look like the
+advance the tape to the end of the existing file entries, backspace over
+the last tape mark, and write the new archive file. If you were to add
+two archives to the example above, the tape might look like the
following:
rrrr*rrrrrr*rrrrr*rr*rrrrr*rrr*rrrr**----------------
\1f
File: tar.info, Node: mt, Prev: Tape Positioning, Up: Many
-9.5.2 The `mt' Utility
+9.5.2 The 'mt' Utility
----------------------
_(This message will disappear, once this node revised.)_
-*Note Blocking Factor::.
+ *Note Blocking Factor::.
- You can use the `mt' utility to advance or rewind a tape past a
+ You can use the 'mt' utility to advance or rewind a tape past a
specified number of archive files on the tape. This will allow you to
move to the beginning of an archive before extracting or reading it, or
to the end of all the archives before writing a new one.
- The syntax of the `mt' command is:
+ The syntax of the 'mt' command is:
mt [-f TAPENAME] OPERATION [NUMBER]
of times an operation is performed (with a default of one), and
OPERATION is one of the following:
-`eof'
-`weof'
+'eof'
+'weof'
Writes NUMBER tape marks at the current position on the tape.
-`fsf'
+'fsf'
Moves tape position forward NUMBER files.
-`bsf'
+'bsf'
Moves tape position back NUMBER files.
-`rewind'
+'rewind'
Rewinds the tape. (Ignores NUMBER.)
-`offline'
-`rewoff1'
+'offline'
+'rewoff1'
Rewinds the tape and takes the tape device off-line. (Ignores
NUMBER.)
-`status'
+'status'
Prints status information about the tape unit.
+ If you don't specify a TAPENAME, 'mt' uses the environment variable
+'TAPE'; if 'TAPE' is not set, 'mt' will use the default device specified
+in your 'sys/mtio.h' file ('DEFTAPE' variable). If this is not defined,
+the program will display a descriptive error message and exit with code
+1.
- If you don't specify a TAPENAME, `mt' uses the environment variable
-`TAPE'; if `TAPE' is not set, `mt' will use the default device
-specified in your `sys/mtio.h' file (`DEFTAPE' variable). If this is
-not defined, the program will display a descriptive error message and
-exit with code 1.
-
- `mt' returns a 0 exit status when the operation(s) were successful,
-1 if the command was unrecognized, and 2 if an operation failed.
+ 'mt' returns a 0 exit status when the operation(s) were successful, 1
+if the command was unrecognized, and 2 if an operation failed.
\1f
File: tar.info, Node: Using Multiple Tapes, Next: label, Prev: Many, Up: Media
Often you might want to write a large archive, one larger than will fit
on the actual tape you are using. In such a case, you can run multiple
-`tar' commands, but this can be inconvenient, particularly if you are
-using options like `--exclude=PATTERN' or dumping entire file systems.
-Therefore, `tar' provides a special mode for creating multi-volume
+'tar' commands, but this can be inconvenient, particularly if you are
+using options like '--exclude=PATTERN' or dumping entire file systems.
+Therefore, 'tar' provides a special mode for creating multi-volume
archives.
- "Multi-volume" archive is a single `tar' archive, stored on several
+ "Multi-volume" archive is a single 'tar' archive, stored on several
media volumes of fixed size. Although in this section we will often
-call `volume' a "tape", there is absolutely no requirement for
+call 'volume' a "tape", there is absolutely no requirement for
multi-volume archives to be stored on tapes. Instead, they can use
whatever media type the user finds convenient, they can even be located
on files.
- When creating a multi-volume archive, GNU `tar' continues to fill
+ When creating a multi-volume archive, GNU 'tar' continues to fill
current volume until it runs out of space, then it switches to next
volume (usually the operator is queried to replace the tape on this
point), and continues working on the new volume. This operation
-continues until all requested files are dumped. If GNU `tar' detects
+continues until all requested files are dumped. If GNU 'tar' detects
end of media while dumping a file, such a file is archived in split
form. Some very big files can even be split across several volumes.
- Each volume is itself a valid GNU `tar' archive, so it can be read
+ Each volume is itself a valid GNU 'tar' archive, so it can be read
without any special options. Consequently any file member residing
entirely on one volume can be extracted or otherwise operated upon
without needing the other volume. Sure enough, to extract a split
Multi-volume archives suffer from several limitations. In
particular, they cannot be compressed.
- GNU `tar' is able to create multi-volume archives of two formats
-(*note Formats::): `GNU' and `POSIX'.
+ GNU 'tar' is able to create multi-volume archives of two formats
+(*note Formats::): 'GNU' and 'POSIX'.
* Menu:
-------------------------------------------
To create an archive that is larger than will fit on a single unit of
-the media, use the `--multi-volume' (`-M') option in conjunction with
-the `--create' option (*note create::). A "multi-volume" archive can
-be manipulated like any other archive (provided the `--multi-volume'
-option is specified), but is stored on more than one tape or file.
-
- When you specify `--multi-volume', `tar' does not report an error
-when it comes to the end of an archive volume (when reading), or the
-end of the media (when writing). Instead, it prompts you to load a new
-storage volume. If the archive is on a magnetic tape, you should
-change tapes when you see the prompt; if the archive is on a floppy
-disk, you should change disks; etc.
-
-`--multi-volume'
-`-M'
+the media, use the '--multi-volume' ('-M') option in conjunction with
+the '--create' option (*note create::). A "multi-volume" archive can be
+manipulated like any other archive (provided the '--multi-volume' option
+is specified), but is stored on more than one tape or file.
+
+ When you specify '--multi-volume', 'tar' does not report an error
+when it comes to the end of an archive volume (when reading), or the end
+of the media (when writing). Instead, it prompts you to load a new
+storage volume. If the archive is on a magnetic tape, you should change
+tapes when you see the prompt; if the archive is on a floppy disk, you
+should change disks; etc.
+
+'--multi-volume'
+'-M'
Creates a multi-volume archive, when used in conjunction with
- `--create' (`-c'). To perform any other operation on a
- multi-volume archive, specify `--multi-volume' in conjunction with
+ '--create' ('-c'). To perform any other operation on a
+ multi-volume archive, specify '--multi-volume' in conjunction with
that operation. For example:
$ tar --create --multi-volume --file=/dev/tape FILES
- The method `tar' uses to detect end of tape is not perfect, and
-fails on some operating systems or on some devices. If `tar' cannot
-detect the end of the tape itself, you can use `--tape-length' option
-to inform it about the capacity of the tape:
+ The method 'tar' uses to detect end of tape is not perfect, and fails
+on some operating systems or on some devices. If 'tar' cannot detect
+the end of the tape itself, you can use '--tape-length' option to inform
+it about the capacity of the tape:
-`--tape-length=SIZE[SUF]'
-`-L SIZE[SUF]'
- Set maximum length of a volume. The SUF, if given, specifies
- units in which SIZE is expressed, e.g. `2M' mean 2 megabytes
- (*note Table 9.1: size-suffixes, for a list of allowed size
- suffixes). Without SUF, units of 1024 bytes (kilobyte) are
- assumed.
+'--tape-length=SIZE[SUF]'
+'-L SIZE[SUF]'
+ Set maximum length of a volume. The SUF, if given, specifies units
+ in which SIZE is expressed, e.g. '2M' mean 2 megabytes (*note
+ Table 9.1: size-suffixes, for a list of allowed size suffixes).
+ Without SUF, units of 1024 bytes (kilobyte) are assumed.
- This option selects `--multi-volume' automatically. For example:
+ This option selects '--multi-volume' automatically. For example:
$ tar --create --tape-length=41943040 --file=/dev/tape FILES
$ tar --create --tape-length=4G --file=/dev/tape FILES
- When GNU `tar' comes to the end of a storage media, it asks you to
+ When GNU 'tar' comes to the end of a storage media, it asks you to
change the volume. The built-in prompt for POSIX locale is(1):
Prepare volume #N for 'ARCHIVE' and hit return:
-where N is the ordinal number of the volume to be created and ARCHIVE
-is archive file or device name.
+where N is the ordinal number of the volume to be created and ARCHIVE is
+archive file or device name.
- When prompting for a new tape, `tar' accepts any of the following
+ When prompting for a new tape, 'tar' accepts any of the following
responses:
-`?'
- Request `tar' to explain possible responses.
-
-`q'
- Request `tar' to exit immediately.
-
-`n FILE-NAME'
- Request `tar' to write the next volume on the file FILE-NAME.
-
-`!'
- Request `tar' to run a subshell. This option can be disabled by
- giving `--restrict' command line option to `tar'(2).
-
-`y'
- Request `tar' to begin writing the next volume.
-
- (You should only type `y' after you have changed the tape; otherwise
-`tar' will write over the volume it just finished.)
-
- The volume number used by `tar' in its tape-changing prompt can be
-changed; if you give the `--volno-file=FILE-OF-NUMBER' option, then
+'?'
+ Request 'tar' to explain possible responses.
+'q'
+ Request 'tar' to exit immediately.
+'n FILE-NAME'
+ Request 'tar' to write the next volume on the file FILE-NAME.
+'!'
+ Request 'tar' to run a subshell. This option can be disabled by
+ giving '--restrict' command line option to 'tar'(2).
+'y'
+ Request 'tar' to begin writing the next volume.
+
+ (You should only type 'y' after you have changed the tape; otherwise
+'tar' will write over the volume it just finished.)
+
+ The volume number used by 'tar' in its tape-changing prompt can be
+changed; if you give the '--volno-file=FILE-OF-NUMBER' option, then
FILE-OF-NUMBER should be an non-existing file to be created, or else, a
file already containing a decimal number. That number will be used as
-the volume number of the first volume written. When `tar' is finished,
-it will rewrite the file with the now-current volume number. (This does
+the volume number of the first volume written. When 'tar' is finished,
+it will rewrite the file with the now-current volume number. (This does
not change the volume number written on a tape label, as per *note
label::, it _only_ affects the number used in the prompt.)
If you want more elaborate behavior than this, you can write a
special "new volume script", that will be responsible for changing the
-volume, and instruct `tar' to use it instead of its normal prompting
+volume, and instruct 'tar' to use it instead of its normal prompting
procedure:
-`--info-script=COMMAND'
-`--new-volume-script=COMMAND'
-`-F COMMAND'
+'--info-script=COMMAND'
+'--new-volume-script=COMMAND'
+'-F COMMAND'
Specify the command to invoke when switching volumes. The COMMAND
can be used to eject cassettes, or to broadcast messages such as
- `Someone please come change my tape' when performing unattended
+ 'Someone please come change my tape' when performing unattended
backups.
The COMMAND can contain additional options, if such are needed.
*Note Running External Commands: external, for a detailed discussion of
-the way GNU `tar' runs external commands. It inherits `tar''s shell
+the way GNU 'tar' runs external commands. It inherits 'tar''s shell
environment. Additional data is passed to it via the following
environment variables:
-`TAR_VERSION'
- GNU `tar' version number.
+'TAR_VERSION'
+ GNU 'tar' version number.
-`TAR_ARCHIVE'
- The name of the archive `tar' is processing.
+'TAR_ARCHIVE'
+ The name of the archive 'tar' is processing.
-`TAR_BLOCKING_FACTOR'
+'TAR_BLOCKING_FACTOR'
Current blocking factor (*note Blocking::).
-`TAR_VOLUME'
- Ordinal number of the volume `tar' is about to start.
+'TAR_VOLUME'
+ Ordinal number of the volume 'tar' is about to start.
-`TAR_SUBCOMMAND'
- A short option describing the operation `tar' is executing. *Note
+'TAR_SUBCOMMAND'
+ A short option describing the operation 'tar' is executing. *Note
Operations::, for a complete list of subcommand options.
-`TAR_FORMAT'
- Format of the archive being processed. *Note Formats::, for a
+'TAR_FORMAT'
+ Format of the archive being processed. *Note Formats::, for a
complete list of archive format names.
-`TAR_FD'
+'TAR_FD'
File descriptor which can be used to communicate the new volume
- name to `tar'.
+ name to 'tar'.
- These variables can be used in the COMMAND itself, provided that
-they are properly quoted to prevent them from being expanded by the
-shell that invokes `tar'.
+ These variables can be used in the COMMAND itself, provided that they
+are properly quoted to prevent them from being expanded by the shell
+that invokes 'tar'.
- The volume script can instruct `tar' to use new archive name, by
-writing in to file descriptor `$TAR_FD' (see below for an example).
+ The volume script can instruct 'tar' to use new archive name, by
+writing in to file descriptor '$TAR_FD' (see below for an example).
- If the info script fails, `tar' exits; otherwise, it begins writing
+ If the info script fails, 'tar' exits; otherwise, it begins writing
the next volume.
- If you want `tar' to cycle through a series of files or tape drives,
+ If you want 'tar' to cycle through a series of files or tape drives,
there are three approaches to choose from. First of all, you can give
-`tar' multiple `--file' options. In this case the specified files will
+'tar' multiple '--file' options. In this case the specified files will
be used, in sequence, as the successive volumes of the archive. Only
-when the first one in the sequence needs to be used again will `tar'
-prompt for a tape change (or run the info script). For example,
-suppose someone has two tape drives on a system named `/dev/tape0' and
-`/dev/tape1'. For having GNU `tar' to switch to the second drive when
+when the first one in the sequence needs to be used again will 'tar'
+prompt for a tape change (or run the info script). For example, suppose
+someone has two tape drives on a system named '/dev/tape0' and
+'/dev/tape1'. For having GNU 'tar' to switch to the second drive when
it needs to write the second tape, and then back to the first tape,
etc., just do either of:
$ tar --create --multi-volume --file=/dev/tape0 --file=/dev/tape1 FILES
$ tar -cM -f /dev/tape0 -f /dev/tape1 FILES
- The second method is to use the `n' response to the tape-change
+ The second method is to use the 'n' response to the tape-change
prompt.
Finally, the most flexible approach is to use a volume script, that
-writes new archive name to the file descriptor `$TAR_FD'. For example,
+writes new archive name to the file descriptor '$TAR_FD'. For example,
the following volume script will create a series of archive files, named
-`ARCHIVE-VOL', where ARCHIVE is the name of the archive being created
-(as given by `--file' option) and VOL is the ordinal number of the
+'ARCHIVE-VOL', where ARCHIVE is the name of the archive being created
+(as given by '--file' option) and VOL is the ordinal number of the
archive being created:
#! /bin/bash
# Extract from the created archive:
$ tar -x -f archive.tar -F new-volume .
-Notice, that the first command had to use `-L' option, since otherwise
-GNU `tar' will end up writing everything to file `archive.tar'.
+Notice, that the first command had to use '-L' option, since otherwise
+GNU 'tar' will end up writing everything to file 'archive.tar'.
You can read each individual volume of a multi-volume archive as if
it were an archive by itself. For example, to list the contents of one
-volume, use `--list', without `--multi-volume' specified. To extract
-an archive member from one volume (assuming it is described that
-volume), use `--extract', again without `--multi-volume'.
+volume, use '--list', without '--multi-volume' specified. To extract an
+archive member from one volume (assuming it is described that volume),
+use '--extract', again without '--multi-volume'.
If an archive member is split across volumes (i.e., its entry begins
on one volume of the media and ends on another), you need to specify
-`--multi-volume' to extract it successfully. In this case, you should
-load the volume where the archive member starts, and use `tar --extract
---multi-volume'--`tar' will prompt for later volumes as it needs them.
+'--multi-volume' to extract it successfully. In this case, you should
+load the volume where the archive member starts, and use 'tar --extract
+--multi-volume'--'tar' will prompt for later volumes as it needs them.
*Note extracting archives::, for more information about extracting
archives.
of the archive media (and new volumes, if needed). For all other
operations, you need to use the entire archive.
- If a multi-volume archive was labeled using `--label=ARCHIVE-LABEL'
-(*note label::) when it was created, `tar' will not automatically label
+ If a multi-volume archive was labeled using '--label=ARCHIVE-LABEL'
+(*note label::) when it was created, 'tar' will not automatically label
volumes which are added later. To label subsequent volumes, specify
-`--label=ARCHIVE-LABEL' again in conjunction with the `--append',
-`--update' or `--concatenate' operation.
+'--label=ARCHIVE-LABEL' again in conjunction with the '--append',
+'--update' or '--concatenate' operation.
Notice that multi-volume support is a GNU extension and the archives
-created in this mode should be read only using GNU `tar'. If you
-absolutely have to process such archives using a third-party `tar'
+created in this mode should be read only using GNU 'tar'. If you
+absolutely have to process such archives using a third-party 'tar'
implementation, read *note Split Recovery::.
---------- Footnotes ----------
- (1) If you run GNU `tar' under a different locale, the translation
-to the locale's language will be used.
+ (1) If you run GNU 'tar' under a different locale, the translation to
+the locale's language will be used.
(2) *Note --restrict::, for more information about this option.
_(This message will disappear, once this node revised.)_
-To give the archive a name which will be recorded in it, use the
-`--label=VOLUME-LABEL' (`-V VOLUME-LABEL') option. This will write a
-special block identifying VOLUME-LABEL as the name of the archive to
-the front of the archive which will be displayed when the archive is
-listed with `--list'. If you are creating a multi-volume archive with
-`--multi-volume' (*note Using Multiple Tapes::), then the volume label
-will have `Volume NNN' appended to the name you give, where NNN is the
+ To give the archive a name which will be recorded in it, use the
+'--label=VOLUME-LABEL' ('-V VOLUME-LABEL') option. This will write a
+special block identifying VOLUME-LABEL as the name of the archive to the
+front of the archive which will be displayed when the archive is listed
+with '--list'. If you are creating a multi-volume archive with
+'--multi-volume' (*note Using Multiple Tapes::), then the volume label
+will have 'Volume NNN' appended to the name you give, where NNN is the
number of the volume of the archive. If you use the
-`--label=VOLUME-LABEL' option when reading an archive, it checks to
-make sure the label on the tape matches the one you gave. *Note
-label::.
+'--label=VOLUME-LABEL' option when reading an archive, it checks to make
+sure the label on the tape matches the one you gave. *Note label::.
- When `tar' writes an archive to tape, it creates a single tape file.
+ When 'tar' writes an archive to tape, it creates a single tape file.
If multiple archives are written to the same tape, one after the other,
they each get written as separate tape files. When extracting, it is
-necessary to position the tape at the right place before running `tar'.
-To do this, use the `mt' command. For more information on the `mt'
+necessary to position the tape at the right place before running 'tar'.
+To do this, use the 'mt' command. For more information on the 'mt'
command and on the organization of tapes into a sequence of tape files,
see *note mt::.
9.6.3 Concatenate Volumes into a Single Archive
-----------------------------------------------
-Sometimes it is necessary to convert existing GNU `tar' multi-volume
-archive to a single `tar' archive. Simply concatenating all volumes
+Sometimes it is necessary to convert existing GNU 'tar' multi-volume
+archive to a single 'tar' archive. Simply concatenating all volumes
into one will not work, since each volume carries an additional
-information at the beginning. GNU `tar' is shipped with the shell
-script `tarcat' designed for this purpose.
+information at the beginning. GNU 'tar' is shipped with the shell
+script 'tarcat' designed for this purpose.
The script takes a list of files comprising a multi-volume archive
and creates the resulting archive at the standard output. For example:
The script implements a simple heuristics to determine the format of
the first volume file and to decide how to process the rest of the
files. However, it makes no attempt to verify whether the files are
-given in order or even if they are valid `tar' archives. It uses `dd'
+given in order or even if they are valid 'tar' archives. It uses 'dd'
and does not filter its standard error, so you will usually see lots of
spurious messages.
9.7 Including a Label in the Archive
====================================
-To avoid problems caused by misplaced paper labels on the archive
-media, you can include a "label" entry -- an archive member which
-contains the name of the archive -- in the archive itself. Use the
-`--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL') option(1) in conjunction
-with the `--create' operation to include a label entry in the archive
-as it is being created.
+To avoid problems caused by misplaced paper labels on the archive media,
+you can include a "label" entry -- an archive member which contains the
+name of the archive -- in the archive itself. Use the
+'--label=ARCHIVE-LABEL' ('-V ARCHIVE-LABEL') option(1) in conjunction
+with the '--create' operation to include a label entry in the archive as
+it is being created.
-`--label=ARCHIVE-LABEL'
-`-V ARCHIVE-LABEL'
+'--label=ARCHIVE-LABEL'
+'-V ARCHIVE-LABEL'
Includes an "archive-label" at the beginning of the archive when
the archive is being created, when used in conjunction with the
- `--create' operation. Checks to make sure the archive label
+ '--create' operation. Checks to make sure the archive label
matches the one specified (when used in conjunction with any other
operation).
- If you create an archive using both `--label=ARCHIVE-LABEL' (`-V
-ARCHIVE-LABEL') and `--multi-volume' (`-M'), each volume of the archive
-will have an archive label of the form `ARCHIVE-LABEL Volume N', where
-N is 1 for the first volume, 2 for the next, and so on. *Note Using
+ If you create an archive using both '--label=ARCHIVE-LABEL' ('-V
+ARCHIVE-LABEL') and '--multi-volume' ('-M'), each volume of the archive
+will have an archive label of the form 'ARCHIVE-LABEL Volume N', where N
+is 1 for the first volume, 2 for the next, and so on. *Note Using
Multiple Tapes::, for information on creating multiple volume archives.
- The volume label will be displayed by `--list' along with the file
+ The volume label will be displayed by '--list' along with the file
contents. If verbose display is requested, it will also be explicitly
marked as in the example below:
V--------- 0/0 0 1992-03-07 12:01 iamalabel--Volume Header--
-rw-r--r-- ringo/user 40 1990-05-21 13:30 iamafilename
- However, `--list' option will cause listing entire contents of the
-archive, which may be undesirable (for example, if the archive is
-stored on a tape). You can request checking only the volume label by
-specifying `--test-label' option. This option reads only the first
+ However, '--list' option will cause listing entire contents of the
+archive, which may be undesirable (for example, if the archive is stored
+on a tape). You can request checking only the volume label by
+specifying '--test-label' option. This option reads only the first
block of an archive, so it can be used with slow storage devices. For
example:
$ tar --test-label --file=iamanarchive
iamalabel
- If `--test-label' is used with one or more command line arguments,
-`tar' compares the volume label with each argument. It exits with code
+ If '--test-label' is used with one or more command line arguments,
+'tar' compares the volume label with each argument. It exits with code
0 if a match is found, and with code 1 otherwise(2). No output is
-displayed, unless you also used the `--verbose' option. For example:
+displayed, unless you also used the '--verbose' option. For example:
$ tar --test-label --file=iamanarchive 'iamalabel'
=> 0
$ tar --test-label --file=iamanarchive 'alabel'
=> 1
- When used with the `--verbose' option, `tar' prints the actual
-volume label (if any), and a verbose diagnostics in case of a mismatch:
+ When used with the '--verbose' option, 'tar' prints the actual volume
+label (if any), and a verbose diagnostics in case of a mismatch:
$ tar --test-label --verbose --file=iamanarchive 'iamalabel'
iamalabel
tar: Archive label mismatch
=> 1
- If you request any operation, other than `--create', along with
-using `--label' option, `tar' will first check if the archive label
-matches the one specified and will refuse to proceed if it does not.
-Use this as a safety precaution to avoid accidentally overwriting
-existing archives. For example, if you wish to add files to `archive',
-presumably labeled with string `My volume', you will get:
+ If you request any operation, other than '--create', along with using
+'--label' option, 'tar' will first check if the archive label matches
+the one specified and will refuse to proceed if it does not. Use this
+as a safety precaution to avoid accidentally overwriting existing
+archives. For example, if you wish to add files to 'archive',
+presumably labeled with string 'My volume', you will get:
$ tar -rf archive --label 'My volume' .
tar: Archive not labeled to match 'My volume'
-in case its label does not match. This will work even if `archive' is
+in case its label does not match. This will work even if 'archive' is
not labeled at all.
- Similarly, `tar' will refuse to list or extract the archive if its
+ Similarly, 'tar' will refuse to list or extract the archive if its
label doesn't match the ARCHIVE-LABEL specified. In those cases,
ARCHIVE-LABEL argument is interpreted as a globbing-style pattern which
must match the actual magnetic volume label. *Note exclude::, for a
precise description of how match is attempted(3). If the switch
-`--multi-volume' (`-M') is being used, the volume label matcher will
-also suffix ARCHIVE-LABEL by ` Volume [1-9]*' if the initial match
+'--multi-volume' ('-M') is being used, the volume label matcher will
+also suffix ARCHIVE-LABEL by ' Volume [1-9]*' if the initial match
fails, before giving up. Since the volume numbering is automatically
-added in labels at creation time, it sounded logical to equally help
-the user taking care of it when the archive is being read.
+added in labels at creation time, it sounded logical to equally help the
+user taking care of it when the archive is being read.
- You can also use `--label' to get a common information on all tapes
+ You can also use '--label' to get a common information on all tapes
of a series. For having this information different in each series
created through a single script used on a regular basis, just manage to
get some date string as part of the label. For example:
Some more notes about volume labels:
- * Each label has its own date and time, which corresponds to the
- time when GNU `tar' initially attempted to write it, often soon
- after the operator launches `tar' or types the carriage return
- telling that the next tape is ready.
+ * Each label has its own date and time, which corresponds to the time
+ when GNU 'tar' initially attempted to write it, often soon after
+ the operator launches 'tar' or types the carriage return telling
+ that the next tape is ready.
* Comparing date labels to get an idea of tape throughput is
unreliable. It gives correct results only if the delays for
---------- Footnotes ----------
- (1) Until version 1.10, that option was called `--volume', but is
-not available under that name anymore.
+ (1) Until version 1.10, that option was called '--volume', but is not
+available under that name anymore.
- (2) Note that GNU `tar' versions up to 1.23 indicated mismatch with
+ (2) Note that GNU 'tar' versions up to 1.23 indicated mismatch with
an exit code 2 and printed a spurious diagnostics on stderr.
- (3) Previous versions of `tar' used full regular expression
-matching, or before that, only exact string matching, instead of
-wildcard matchers. We decided for the sake of simplicity to use a
-uniform matching device through `tar'.
+ (3) Previous versions of 'tar' used full regular expression matching,
+or before that, only exact string matching, instead of wildcard
+matchers. We decided for the sake of simplicity to use a uniform
+matching device through 'tar'.
\1f
File: tar.info, Node: verify, Next: Write Protection, Prev: label, Up: Media
9.8 Verifying Data as It is Stored
==================================
-`-W'
-`--verify'
+'-W'
+'--verify'
Attempt to verify the archive after writing.
- This option causes `tar' to verify the archive after writing it.
+ This option causes 'tar' to verify the archive after writing it.
Each volume is checked after it is written, and any discrepancies are
recorded on the standard error output.
devices cannot be verified.
You can insure the accuracy of an archive by comparing files in the
-system with archive members. `tar' can compare an archive to the file
+system with archive members. 'tar' can compare an archive to the file
system as the archive is being written, to verify a write operation, or
can compare a previously written archive, to insure that it is up to
date.
To check for discrepancies in an archive immediately after it is
-written, use the `--verify' (`-W') option in conjunction with the
-`--create' operation. When this option is specified, `tar' checks
+written, use the '--verify' ('-W') option in conjunction with the
+'--create' operation. When this option is specified, 'tar' checks
archive members against their counterparts in the file system, and
reports discrepancies on the standard error.
drives, and some other devices cannot be verified.
One can explicitly compare an already made archive with the file
-system by using the `--compare' (`--diff', `-d') option, instead of
-using the more automatic `--verify' option. *Note compare::.
+system by using the '--compare' ('--diff', '-d') option, instead of
+using the more automatic '--verify' option. *Note compare::.
Note that these two options have a slightly different intent. The
-`--compare' option checks how identical are the logical contents of some
-archive with what is on your disks, while the `--verify' option is
+'--compare' option checks how identical are the logical contents of some
+archive with what is on your disks, while the '--verify' option is
really for checking if the physical contents agree and if the recording
-media itself is of dependable quality. So, for the `--verify'
-operation, `tar' tries to defeat all in-memory cache pertaining to the
+media itself is of dependable quality. So, for the '--verify'
+operation, 'tar' tries to defeat all in-memory cache pertaining to the
archive, while it lets the speed optimization undisturbed for the
-`--compare' option. If you nevertheless use `--compare' for media
-verification, you may have to defeat the in-memory cache yourself,
-maybe by opening and reclosing the door latch of your recording unit,
-forcing some doubt in your operating system about the fact this is
-really the same volume as the one just written or read.
+'--compare' option. If you nevertheless use '--compare' for media
+verification, you may have to defeat the in-memory cache yourself, maybe
+by opening and reclosing the door latch of your recording unit, forcing
+some doubt in your operating system about the fact this is really the
+same volume as the one just written or read.
- The `--verify' option would not be necessary if drivers were indeed
+ The '--verify' option would not be necessary if drivers were indeed
able to detect dependably all write failures. This sometimes require
many magnetic heads, some able to read after the writes occurred. One
would not say that drivers unable to detect all cases are necessarily
flawed, as long as programming is concerned.
- The `--verify' (`-W') option will not work in conjunction with the
-`--multi-volume' (`-M') option or the `--append' (`-r'), `--update'
-(`-u') and `--delete' operations. *Note Operations::, for more
+ The '--verify' ('-W') option will not work in conjunction with the
+'--multi-volume' ('-M') option or the '--append' ('-r'), '--update'
+('-u') and '--delete' operations. *Note Operations::, for more
information on these operations.
- Also, since `tar' normally strips leading `/' from file names (*note
-absolute::), a command like `tar --verify -cf /tmp/foo.tar /etc' will
-work as desired only if the working directory is `/', as `tar' uses the
-archive's relative member names (e.g., `etc/motd') when verifying the
+ Also, since 'tar' normally strips leading '/' from file names (*note
+absolute::), a command like 'tar --verify -cf /tmp/foo.tar /etc' will
+work as desired only if the working directory is '/', as 'tar' uses the
+archive's relative member names (e.g., 'etc/motd') when verifying the
archive.
\1f
Almost all tapes and diskettes, and in a few rare cases, even disks can
be "write protected", to protect data on them from being changed. Once
-an archive is written, you should write protect the media to prevent
-the archive from being accidentally overwritten or deleted. (This will
+an archive is written, you should write protect the media to prevent the
+archive from being accidentally overwritten or deleted. (This will
protect the archive from being changed with a tape or floppy drive--it
will not protect it from magnet fields or other physical hazards.)
The write protection device itself is usually an integral part of the
-physical media, and can be a two position (write enabled/write
-disabled) switch, a notch which can be popped out or covered, a ring
-which can be removed from the center of a tape reel, or some other
-changeable feature.
+physical media, and can be a two position (write enabled/write disabled)
+switch, a notch which can be popped out or covered, a ring which can be
+removed from the center of a tape reel, or some other changeable
+feature.
\1f
File: tar.info, Node: Reliability and security, Next: Changes, Prev: Media, Up: Top
10 Reliability and Security
***************************
-The `tar' command reads and writes files as any other application does,
+The 'tar' command reads and writes files as any other application does,
and is subject to the usual caveats about reliability and security.
This section contains some commonsense advice on the topic.
10.1 Reliability
================
-Ideally, when `tar' is creating an archive, it reads from a file system
+Ideally, when 'tar' is creating an archive, it reads from a file system
that is not being modified, and encounters no errors or inconsistencies
while reading and writing. If this is the case, the archive should
faithfully reflect what was read. Similarly, when extracting from an
-archive, ideally `tar' ideally encounters no errors and the extracted
+archive, ideally 'tar' ideally encounters no errors and the extracted
files faithfully reflect what was in the archive.
However, when reading or writing real-world file systems, several
10.1.1 Permissions Problems
---------------------------
-If `tar' encounters errors while reading or writing files, it normally
+If 'tar' encounters errors while reading or writing files, it normally
reports an error and exits with nonzero status. The work it does may
therefore be incomplete. For example, when creating an archive, if
-`tar' cannot read a file then it cannot copy the file into the archive.
+'tar' cannot read a file then it cannot copy the file into the archive.
\1f
File: tar.info, Node: Data corruption and repair, Next: Race conditions, Prev: Permissions problems, Up: Reliability
If an archive becomes corrupted by an I/O error, this may corrupt the
data in an extracted file. Worse, it may corrupt the file's metadata,
-which may cause later parts of the archive to become misinterpreted.
-An tar-format archive contains a checksum that most likely will detect
+which may cause later parts of the archive to become misinterpreted. An
+tar-format archive contains a checksum that most likely will detect
errors in the metadata, but it will not detect errors in the data.
If data corruption is a concern, you can compute and check your own
-checksums of an archive by using other programs, such as `cksum'.
+checksums of an archive by using other programs, such as 'cksum'.
When attempting to recover from a read error or data corruption in an
archive, you may need to skip past the questionable data and read the
-rest of the archive. This requires some expertise in the archive
-format and in other software tools.
+rest of the archive. This requires some expertise in the archive format
+and in other software tools.
\1f
File: tar.info, Node: Race conditions, Prev: Data corruption and repair, Up: Reliability
10.1.3 Race conditions
----------------------
-If some other process is modifying the file system while `tar' is
+If some other process is modifying the file system while 'tar' is
reading or writing files, the result may well be inconsistent due to
race conditions. For example, if another process creates some files in
-a directory while `tar' is creating an archive containing the
-directory's files, `tar' may see some of the files but not others, or
-it may see a file that is in the process of being created. The
-resulting archive may not be a snapshot of the file system at any point
-in time. If an application such as a database system depends on an
-accurate snapshot, restoring from the `tar' archive of a live file
-system may therefore break that consistency and may break the
-application. The simplest way to avoid the consistency issues is to
-avoid making other changes to the file system while tar is reading it
-or writing it.
+a directory while 'tar' is creating an archive containing the
+directory's files, 'tar' may see some of the files but not others, or it
+may see a file that is in the process of being created. The resulting
+archive may not be a snapshot of the file system at any point in time.
+If an application such as a database system depends on an accurate
+snapshot, restoring from the 'tar' archive of a live file system may
+therefore break that consistency and may break the application. The
+simplest way to avoid the consistency issues is to avoid making other
+changes to the file system while tar is reading it or writing it.
When creating an archive, several options are available to avoid race
conditions. Some hosts have a way of snapshotting a file system, or of
-temporarily suspending all changes to a file system, by (say)
-suspending the only virtual machine that can modify a file system; if
-you use these facilities and have `tar -c' read from a snapshot when
-creating an archive, you can avoid inconsistency problems. More
-drastically, before starting `tar' you could suspend or shut down all
-processes other than `tar' that have access to the file system, or you
-could unmount the file system and then mount it read-only.
+temporarily suspending all changes to a file system, by (say) suspending
+the only virtual machine that can modify a file system; if you use these
+facilities and have 'tar -c' read from a snapshot when creating an
+archive, you can avoid inconsistency problems. More drastically, before
+starting 'tar' you could suspend or shut down all processes other than
+'tar' that have access to the file system, or you could unmount the file
+system and then mount it read-only.
When extracting from an archive, one approach to avoid race
conditions is to create a directory that no other process can write to,
10.2 Security
=============
-In some cases `tar' may be used in an adversarial situation, where an
+In some cases 'tar' may be used in an adversarial situation, where an
untrusted user is attempting to gain information about or modify
otherwise-inaccessible files. Dealing with untrusted data (that is,
data generated by an untrusted user) typically requires extra care,
-because even the smallest mistake in the use of `tar' is more likely to
+because even the smallest mistake in the use of 'tar' is more likely to
be exploited by an adversary than by a race condition.
* Menu:
10.2.1 Privacy
--------------
-Standard privacy concerns apply when using `tar'. For example, suppose
-you are archiving your home directory into a file
-`/archive/myhome.tar'. Any secret information in your home directory,
-such as your SSH secret keys, are copied faithfully into the archive.
-Therefore, if your home directory contains any file that should not be
-read by some other user, the archive itself should be not be readable
-by that user. And even if the archive's data are inaccessible to
-untrusted users, its metadata (such as size or last-modified date) may
-reveal some information about your home directory; if the metadata are
-intended to be private, the archive's parent directory should also be
-inaccessible to untrusted users.
-
- One precaution is to create `/archive' so that it is not accessible
+Standard privacy concerns apply when using 'tar'. For example, suppose
+you are archiving your home directory into a file '/archive/myhome.tar'.
+Any secret information in your home directory, such as your SSH secret
+keys, are copied faithfully into the archive. Therefore, if your home
+directory contains any file that should not be read by some other user,
+the archive itself should be not be readable by that user. And even if
+the archive's data are inaccessible to untrusted users, its metadata
+(such as size or last-modified date) may reveal some information about
+your home directory; if the metadata are intended to be private, the
+archive's parent directory should also be inaccessible to untrusted
+users.
+
+ One precaution is to create '/archive' so that it is not accessible
to any user, unless that user also has permission to access all the
files in your home directory.
untrusted user; otherwise, that user could modify the archive, and when
you later extract from the archive you will get incorrect data.
- When `tar' extracts from an archive, by default it writes into files
+ When 'tar' extracts from an archive, by default it writes into files
relative to the working directory. If the archive was generated by an
untrusted user, that user therefore can write into any file under the
-working directory. If the working directory contains a symbolic link
-to another directory, the untrusted user can also write into any file
-under the referenced directory. When extracting from an untrusted
-archive, it is therefore good practice to create an empty directory and
-run `tar' in that directory.
+working directory. If the working directory contains a symbolic link to
+another directory, the untrusted user can also write into any file under
+the referenced directory. When extracting from an untrusted archive, it
+is therefore good practice to create an empty directory and run 'tar' in
+that directory.
When extracting from two or more untrusted archives, each one should
be extracted independently, into different empty directories.
Otherwise, the first archive could create a symbolic link into an area
outside the working directory, and the second one could follow the link
and overwrite data that is not under the working directory. For
-example, when restoring from a series of incremental dumps, the
-archives should have been created by a trusted process, as otherwise
-the incremental restores might alter data outside the working directory.
-
- If you use the `--absolute-names' (`-P') option when extracting,
-`tar' respects any file names in the archive, even file names that
-begin with `/' or contain `..'. As this lets the archive overwrite any
-file in your system that you can write, the `--absolute-names' (`-P')
-option should be used only for trusted archives.
-
- Conversely, with the `--keep-old-files' (`-k') and
-`--skip-old-files' options, `tar' refuses to replace existing files
-when extracting. The difference between the two options is that the
-former treats existing files as errors whereas the latter just silently
-ignores them.
-
- Finally, with the `--no-overwrite-dir' option, `tar' refuses to
+example, when restoring from a series of incremental dumps, the archives
+should have been created by a trusted process, as otherwise the
+incremental restores might alter data outside the working directory.
+
+ If you use the '--absolute-names' ('-P') option when extracting,
+'tar' respects any file names in the archive, even file names that begin
+with '/' or contain '..'. As this lets the archive overwrite any file
+in your system that you can write, the '--absolute-names' ('-P') option
+should be used only for trusted archives.
+
+ Conversely, with the '--keep-old-files' ('-k') and '--skip-old-files'
+options, 'tar' refuses to replace existing files when extracting. The
+difference between the two options is that the former treats existing
+files as errors whereas the latter just silently ignores them.
+
+ Finally, with the '--no-overwrite-dir' option, 'tar' refuses to
replace the permissions or ownership of already-existing directories.
These options may help when extracting from untrusted archives.
Extra care is required when creating from or extracting into a file
system that is accessible to untrusted users. For example, superusers
-who invoke `tar' must be wary about its actions being hijacked by an
+who invoke 'tar' must be wary about its actions being hijacked by an
adversary who is reading or writing the file system at the same time
-that `tar' is operating.
-
- When creating an archive from a live file system, `tar' is
-vulnerable to denial-of-service attacks. For example, an adversarial
-user could create the illusion of an indefinitely-deep directory
-hierarchy `d/e/f/g/...' by creating directories one step ahead of
-`tar', or the illusion of an indefinitely-long file by creating a
-sparse file but arranging for blocks to be allocated just before `tar'
-reads them. There is no easy way for `tar' to distinguish these
-scenarios from legitimate uses, so you may need to monitor `tar', just
-as you'd need to monitor any other system service, to detect such
-attacks.
+that 'tar' is operating.
+
+ When creating an archive from a live file system, 'tar' is vulnerable
+to denial-of-service attacks. For example, an adversarial user could
+create the illusion of an indefinitely-deep directory hierarchy
+'d/e/f/g/...' by creating directories one step ahead of 'tar', or the
+illusion of an indefinitely-long file by creating a sparse file but
+arranging for blocks to be allocated just before 'tar' reads them.
+There is no easy way for 'tar' to distinguish these scenarios from
+legitimate uses, so you may need to monitor 'tar', just as you'd need to
+monitor any other system service, to detect such attacks.
While a superuser is extracting from an archive into a live file
system, an untrusted user might replace a directory with a symbolic
-link, in hopes that `tar' will follow the symbolic link and extract
-data into files that the untrusted user does not have access to. Even
-if the archive was generated by the superuser, it may contain a file
-such as `d/etc/passwd' that the untrusted user earlier created in order
-to break in; if the untrusted user replaces the directory `d/etc' with
-a symbolic link to `/etc' while `tar' is running, `tar' will overwrite
-`/etc/passwd'. This attack can be prevented by extracting into a
+link, in hopes that 'tar' will follow the symbolic link and extract data
+into files that the untrusted user does not have access to. Even if the
+archive was generated by the superuser, it may contain a file such as
+'d/etc/passwd' that the untrusted user earlier created in order to break
+in; if the untrusted user replaces the directory 'd/etc' with a symbolic
+link to '/etc' while 'tar' is running, 'tar' will overwrite
+'/etc/passwd'. This attack can be prevented by extracting into a
directory that is inaccessible to untrusted users.
Similar attacks via symbolic links are also possible when creating an
archive, if the untrusted user can modify an ancestor of a top-level
-argument of `tar'. For example, an untrusted user that can modify
-`/home/eve' can hijack a running instance of `tar -cf -
-/home/eve/Documents/yesterday' by replacing `/home/eve/Documents' with
-a symbolic link to some other location. Attacks like these can be
+argument of 'tar'. For example, an untrusted user that can modify
+'/home/eve' can hijack a running instance of 'tar -cf -
+/home/eve/Documents/yesterday' by replacing '/home/eve/Documents' with a
+symbolic link to some other location. Attacks like these can be
prevented by making sure that untrusted users cannot modify any files
-that are top-level arguments to `tar', or any ancestor directories of
+that are top-level arguments to 'tar', or any ancestor directories of
these files.
\1f
being archived.
* Extract from an untrusted archive only into an otherwise-empty
- directory. This directory and its parent should be accessible
- only to trusted users. For example:
+ directory. This directory and its parent should be accessible only
+ to trusted users. For example:
$ chmod go-rwx .
$ mkdir -m go-rwx dir
programs.
* Do not let untrusted users modify directories that are ancestors of
- top-level arguments of `tar'. For example, while you are
- executing `tar -cf /archive/u-home.tar /u/home', do not let an
- untrusted user modify `/', `/archive', or `/u'.
+ top-level arguments of 'tar'. For example, while you are executing
+ 'tar -cf /archive/u-home.tar /u/home', do not let an untrusted user
+ modify '/', '/archive', or '/u'.
- * Pay attention to the diagnostics and exit status of `tar'.
+ * Pay attention to the diagnostics and exit status of 'tar'.
* When archiving live file systems, monitor running instances of
- `tar' to detect denial-of-service attacks.
-
- * Avoid unusual options such as `--absolute-names' (`-P'),
- `--dereference' (`-h'), `--overwrite', `--recursive-unlink', and
- `--remove-files' unless you understand their security implications.
+ 'tar' to detect denial-of-service attacks.
+ * Avoid unusual options such as '--absolute-names' ('-P'),
+ '--dereference' ('-h'), '--overwrite', '--recursive-unlink', and
+ '--remove-files' unless you understand their security implications.
\1f
File: tar.info, Node: Changes, Next: Configuring Help Summary, Prev: Reliability and security, Up: Top
******************
This appendix lists some important user-visible changes between version
-GNU `tar' 1.28 and previous versions. An up-to-date version of this
-document is available at the GNU `tar' documentation page
+GNU 'tar' 1.29 and previous versions. An up-to-date version of this
+document is available at the GNU 'tar' documentation page
(http://www.gnu.org/software/tar/manual/changes.html).
Use of globbing patterns when listing and extracting.
+
Previous versions of GNU tar assumed shell-style globbing when
extracting from or listing an archive. For example:
$ tar xf foo.tar '*.c'
- would extract all files whose names end in `.c'. This behavior
- was not documented and was incompatible with traditional tar
+ would extract all files whose names end in '.c'. This behavior was
+ not documented and was incompatible with traditional tar
implementations. Therefore, starting from version 1.15.91, GNU tar
no longer uses globbing by default. For example, the above
invocation is now interpreted as a request to extract from the
- archive the file named `*.c'.
+ archive the file named '*.c'.
To facilitate transition to the new behavior for those users who
- got used to the previous incorrect one, `tar' will print a warning
+ got used to the previous incorrect one, 'tar' will print a warning
if it finds out that a requested member was not found in the
archive and its name looks like a globbing pattern. For example:
tar: *.c: Not found in archive
tar: Error exit delayed from previous errors
- To treat member names as globbing patterns, use the `--wildcards'
- option. If you want to tar to mimic the behavior of versions
- prior to 1.15.91, add this option to your `TAR_OPTIONS' variable.
+ To treat member names as globbing patterns, use the '--wildcards'
+ option. If you want to tar to mimic the behavior of versions prior
+ to 1.15.91, add this option to your 'TAR_OPTIONS' variable.
*Note wildcards::, for the detailed discussion of the use of
- globbing patterns by GNU `tar'.
+ globbing patterns by GNU 'tar'.
-Use of short option `-o'.
- Earlier versions of GNU `tar' understood `-o' command line option
- as a synonym for `--old-archive'.
+Use of short option '-o'.
- GNU `tar' starting from version 1.13.90 understands this option as
- a synonym for `--no-same-owner'. This is compatible with UNIX98
- `tar' implementations.
+ Earlier versions of GNU 'tar' understood '-o' command line option
+ as a synonym for '--old-archive'.
- However, to facilitate transition, `-o' option retains its old
+ GNU 'tar' starting from version 1.13.90 understands this option as
+ a synonym for '--no-same-owner'. This is compatible with UNIX98
+ 'tar' implementations.
+
+ However, to facilitate transition, '-o' option retains its old
semantics when it is used with one of archive-creation commands.
- Users are encouraged to use `--format=oldgnu' instead.
+ Users are encouraged to use '--format=oldgnu' instead.
It is especially important, since versions of GNU Automake up to
and including 1.8.4 invoke tar with this option to produce
discussion of this issue and its implications.
*Note tar-formats: (automake)Options, for a description on how to
- use various archive formats with `automake'.
+ use various archive formats with 'automake'.
+
+ Future versions of GNU 'tar' will understand '-o' only as a synonym
+ for '--no-same-owner'.
- Future versions of GNU `tar' will understand `-o' only as a
- synonym for `--no-same-owner'.
+Use of short option '-l'
-Use of short option `-l'
- Earlier versions of GNU `tar' understood `-l' option as a synonym
- for `--one-file-system'. Since such usage contradicted to UNIX98
+ Earlier versions of GNU 'tar' understood '-l' option as a synonym
+ for '--one-file-system'. Since such usage contradicted to UNIX98
specification and harmed compatibility with other implementations,
- it was declared deprecated in version 1.14. However, to
- facilitate transition to its new semantics, it was supported by
- versions 1.15 and 1.15.90. The present use of `-l' as a short
- variant of `--check-links' was introduced in version 1.15.91.
+ it was declared deprecated in version 1.14. However, to facilitate
+ transition to its new semantics, it was supported by versions 1.15
+ and 1.15.90. The present use of '-l' as a short variant of
+ '--check-links' was introduced in version 1.15.91.
+
+Use of options '--portability' and '--old-archive'
+
+ These options are deprecated. Please use '--format=v7' instead.
-Use of options `--portability' and `--old-archive'
- These options are deprecated. Please use `--format=v7' instead.
+Use of option '--posix'
-Use of option `--posix'
- This option is deprecated. Please use `--format=posix' instead.
+ This option is deprecated. Please use '--format=posix' instead.
\1f
File: tar.info, Node: Configuring Help Summary, Next: Fixing Snapshot Files, Prev: Changes, Up: Top
Appendix B Configuring Help Summary
***********************************
-Running `tar --help' displays the short `tar' option summary (*note
-help::). This summary is organized by "groups" of semantically close
-options. The options within each group are printed in the following
+Running 'tar --help' displays the short 'tar' option summary (*note
+help::). This summary is organized by "groups" of semantically close
+options. The options within each group are printed in the following
order: a short option, eventually followed by a list of corresponding
-long option names, followed by a short description of the option. For
-example, here is an excerpt from the actual `tar --help' output:
+long option names, followed by a short description of the option. For
+example, here is an excerpt from the actual 'tar --help' output:
Main operation mode:
--delete delete from the archive
The exact visual representation of the help output is configurable
-via `ARGP_HELP_FMT' environment variable. The value of this variable is
-a comma-separated list of "format variable" assignments. There are two
-kinds of format variables. An "offset variable" keeps the offset of
-some part of help output text from the leftmost column on the screen. A
-"boolean" variable is a flag that toggles some output feature on or
-off. Depending on the type of the corresponding variable, there are two
-kinds of assignments:
+via 'ARGP_HELP_FMT' environment variable. The value of this variable is
+a comma-separated list of "format variable" assignments. There are two
+kinds of format variables. An "offset variable" keeps the offset of
+some part of help output text from the leftmost column on the screen. A
+"boolean" variable is a flag that toggles some output feature on or off.
+Depending on the type of the corresponding variable, there are two kinds
+of assignments:
Offset assignment
+
The assignment to an offset variable has the following syntax:
VARIABLE=VALUE
to be assigned to the variable.
Boolean assignment
- To assign `true' value to a variable, simply put this variable
- name. To assign `false' value, prefix the variable name with
- `no-'. For example:
- # Assign `true' value:
+ To assign 'true' value to a variable, simply put this variable
+ name. To assign 'false' value, prefix the variable name with
+ 'no-'. For example:
+
+ # Assign true value:
dup-args
- # Assign `false' value:
+ # Assign false value:
no-dup-args
Following variables are declared:
-f, --file=ARCHIVE use archive file or device ARCHIVE
and a message indicating that the argument is applicable to both
- forms is printed below the options. This message can be disabled
- using `dup-args-note' (see below).
+ forms is printed below the options. This message can be disabled
+ using 'dup-args-note' (see below).
The default is false.
Mandatory or optional arguments to long options are also
mandatory or optional for any corresponding short options.
- Setting `no-dup-args-note' inhibits this message. Normally, only
- one of variables `dup-args' or `dup-args-note' should be set.
+ Setting 'no-dup-args-note' inhibits this message. Normally, only
+ one of variables 'dup-args' or 'dup-args-note' should be set.
-- Help Output: offset short-opt-col
- Column in which short options start. Default is 2.
+ Column in which short options start. Default is 2.
$ tar --help|grep ARCHIVE
-f, --file=ARCHIVE use archive file or device ARCHIVE
-f, --file=ARCHIVE use archive file or device ARCHIVE
-- Help Output: offset long-opt-col
- Column in which long options start. Default is 6. For example:
+ Column in which long options start. Default is 6. For example:
$ tar --help|grep ARCHIVE
-f, --file=ARCHIVE use archive file or device ARCHIVE
Column in which "doc options" start. A doc option isn't actually
an option, but rather an arbitrary piece of documentation that is
displayed in much the same manner as the options. For example, in
- the description of `--format' option:
+ the description of '--format' option:
-H, --format=FORMAT create archive of the given format.
ustar POSIX 1003.1-1988 (ustar) format
v7 old V7 tar format
- the format names are doc options. Thus, if you set
- `ARGP_HELP_FMT=doc-opt-col=6' the above part of the help output
+ the format names are doc options. Thus, if you set
+ 'ARGP_HELP_FMT=doc-opt-col=6' the above part of the help output
will look as follows:
-H, --format=FORMAT create archive of the given format.
v7 old V7 tar format
-- Help Output: offset opt-doc-col
- Column in which option description starts. Default is 29.
+ Column in which option description starts. Default is 29.
$ tar --help|grep ARCHIVE
-f, --file=ARCHIVE use archive file or device ARCHIVE
use archive file or device ARCHIVE
Notice, that the description starts on a separate line if
- `opt-doc-col' value is too small.
+ 'opt-doc-col' value is too small.
-- Help Output: offset header-col
Column in which "group headers" are printed. A group header is a
-A, --catenate, --concatenate append tar files to
an archive
-c, --create create a new archive
- `Main operation mode:' is the group header.
+ 'Main operation mode:' is the group header.
The default value is 1.
-- Help Output: offset usage-indent
- Indentation of wrapped usage lines. Affects `--usage' output.
+ Indentation of wrapped usage lines. Affects '--usage' output.
Default is 12.
-- Help Output: offset rmargin
- Right margin of the text output. Used for wrapping.
+ Right margin of the text output. Used for wrapping.
\1f
File: tar.info, Node: Fixing Snapshot Files, Next: Tar Internals, Prev: Configuring Help Summary, Up: Top
Various situations can cause device numbers to change: upgrading your
kernel version, reconfiguring your hardware, loading kernel modules in a
different order, using virtual volumes that are assembled dynamically
-(such as with LVM or RAID), hot-plugging drives (e.g. external USB or
+(such as with LVM or RAID), hot-plugging drives (e.g. external USB or
Firewire drives), etc. In the majority of cases this change is
-unnoticed by the users. However, it influences `tar' incremental
+unnoticed by the users. However, it influences 'tar' incremental
backups: the device number is stored in tar snapshot files (*note
Snapshot Files::) and is used to determine whether the file has changed
-since the last backup. If the device numbers change for some reason,
-by default the next backup you run will be a full backup.
+since the last backup. If the device numbers change for some reason, by
+default the next backup you run will be a full backup.
- To minimize the impact in these cases, GNU `tar' comes with the
-`tar-snapshot-edit' utility for inspecting and updating device numbers
-in snapshot files. (The utility, written by Dustin J. Mitchell, is
-also available from the GNU `tar' home page
+ To minimize the impact in these cases, GNU 'tar' comes with the
+'tar-snapshot-edit' utility for inspecting and updating device numbers
+in snapshot files. (The utility, written by Dustin J. Mitchell, is also
+available from the GNU 'tar' home page
(http://www.gnu.org/software/tar/utils/tar-snapshot-edit.html).)
- To obtain a summary of the device numbers found in the snapshot
-file, run
+ To obtain a summary of the device numbers found in the snapshot file,
+run
$ tar-snapshot-edit SNAPFILE
where SNAPFILE is the name of the snapshot file (you can supply as many
files as you wish in a single command line). You can then compare the
numbers across snapshot files, or against those currently in use on the
-live filesystem (using `ls -l' or `stat').
+live filesystem (using 'ls -l' or 'stat').
Assuming the device numbers have indeed changed, it's often possible
-to simply tell GNU `tar' to ignore the device number when processing the
+to simply tell GNU 'tar' to ignore the device number when processing the
incremental snapshot files for these backups, using the
-`--no-check-device' option (*note device numbers::).
+'--no-check-device' option (*note device numbers::).
- Alternatively, you can use the `tar-edit-snapshot' script's `-r'
+ Alternatively, you can use the 'tar-edit-snapshot' script's '-r'
option to update all occurrences of the given device number in the
snapshot file(s). It takes a single argument of the form
-`OLDDEV-NEWDEV', where OLDDEV is the device number used in the
-snapshot file, and NEWDEV is the corresponding new device number. Both
-numbers may be specified in hex (e.g., `0xfe01'), decimal (e.g.,
-`65025'), or as a major:minor number pair (e.g., `254:1'). To change
-several device numbers at once, specify them in a single
-comma-separated list, as in `-r 0x3060-0x4500,0x307-0x4600'.
+'OLDDEV-NEWDEV', where OLDDEV is the device number used in the snapshot
+file, and NEWDEV is the corresponding new device number. Both numbers
+may be specified in hex (e.g., '0xfe01'), decimal (e.g., '65025'), or as
+a major:minor number pair (e.g., '254:1'). To change several device
+numbers at once, specify them in a single comma-separated list, as in
+'-r 0x3060-0x4500,0x307-0x4600'.
Before updating the snapshot file, it is a good idea to create a
-backup copy of it. This is accomplished by `-b' option. The name of
-the backup file is obtained by appending `~' to the original file name.
+backup copy of it. This is accomplished by '-b' option. The name of
+the backup file is obtained by appending '~' to the original file name.
An example session:
$ tar-snapshot-edit root_snap.0 boot_snap.0
_(This message will disappear, once this node revised.)_
-While an archive may contain many files, the archive itself is a single
-ordinary file. Like any other file, an archive file can be written to
-a storage device such as a tape or disk, sent through a pipe or over a
-network, saved on the active file system, or even stored in another
-archive. An archive file is not easy to read or manipulate without
-using the `tar' utility or Tar mode in GNU Emacs.
+ While an archive may contain many files, the archive itself is a
+single ordinary file. Like any other file, an archive file can be
+written to a storage device such as a tape or disk, sent through a pipe
+or over a network, saved on the active file system, or even stored in
+another archive. An archive file is not easy to read or manipulate
+without using the 'tar' utility or Tar mode in GNU Emacs.
Physically, an archive consists of a series of file entries
terminated by an end-of-archive entry, which consists of two 512 blocks
of zero bytes. A file entry usually describes one of the files in the
archive (an "archive member"), and consists of a file header and the
contents of the file. File headers contain file names and statistics,
-checksum information which `tar' uses to detect file corruption, and
+checksum information which 'tar' uses to detect file corruption, and
information about file types.
Archives are permitted to have more than one member with the same
member name. One way this situation can occur is if more than one
-version of a file has been stored in the archive. For information
-about adding new versions of a file to an archive, see *note update::.
+version of a file has been stored in the archive. For information about
+adding new versions of a file to an archive, see *note update::.
In addition to entries describing archive members, an archive may
-contain entries which `tar' itself uses to store information. *Note
+contain entries which 'tar' itself uses to store information. *Note
label::, for an example of such an archive entry.
- A `tar' archive file contains a series of blocks. Each block
-contains `BLOCKSIZE' bytes. Although this format may be thought of as
+ A 'tar' archive file contains a series of blocks. Each block
+contains 'BLOCKSIZE' bytes. Although this format may be thought of as
being on magnetic tape, other media are often used.
Each file archived is represented by a header block which describes
-the file, followed by zero or more blocks which give the contents of
-the file. At the end of the archive file there are two 512-byte blocks
+the file, followed by zero or more blocks which give the contents of the
+file. At the end of the archive file there are two 512-byte blocks
filled with binary zeros as an end-of-file marker. A reasonable system
should write such end-of-file marker at the end of an archive, but must
not assume that such a block exists when reading an archive. In
-particular GNU `tar' always issues a warning if it does not encounter
+particular GNU 'tar' always issues a warning if it does not encounter
it.
- The blocks may be "blocked" for physical I/O operations. Each
-record of N blocks (where N is set by the `--blocking-factor=512-SIZE'
-(`-b 512-SIZE') option to `tar') is written with a single `write ()'
+ The blocks may be "blocked" for physical I/O operations. Each record
+of N blocks (where N is set by the '--blocking-factor=512-SIZE' ('-b
+512-SIZE') option to 'tar') is written with a single 'write ()'
operation. On magnetic tapes, the result of such a write is a single
record. When writing an archive, the last record of blocks should be
written at the full size, with blocks after the zero block containing
-all zeros. When reading an archive, a reasonable system should
-properly handle an archive whose last record is shorter than the rest,
-or which contains garbage records after a zero block.
+all zeros. When reading an archive, a reasonable system should properly
+handle an archive whose last record is shorter than the rest, or which
+contains garbage records after a zero block.
- The header block is defined in C as follows. In the GNU `tar'
-distribution, this is part of file `src/tar.h':
+ The header block is defined in C as follows. In the GNU 'tar'
+distribution, this is part of file 'src/tar.h':
/* tar Header Block, from POSIX 1003.1-1990. */
char isextended;
};
+
All characters in header blocks are represented by using 8-bit
-characters in the local variant of ASCII. Each field within the
+characters in the local variant of ASCII. Each field within the
structure is contiguous; that is, there is no padding used within the
structure. Each character on the archive medium is stored contiguously.
Bytes representing the contents of files (after the header block of
each file) are not translated in any way and are not constrained to
-represent characters in any character set. The `tar' format does not
+represent characters in any character set. The 'tar' format does not
distinguish text files from binary files, and no translation of file
contents is performed.
- The `name', `linkname', `magic', `uname', and `gname' are
+ The 'name', 'linkname', 'magic', 'uname', and 'gname' are
null-terminated character strings. All other fields are zero-filled
-octal numbers in ASCII. Each numeric field of width W contains W minus
-1 digits, and a null.
+octal numbers in ASCII. Each numeric field of width W contains W minus 1
+digits, and a null.
- The `name' field is the file name of the file, with directory names
+ The 'name' field is the file name of the file, with directory names
(if any) preceding the file name, separated by slashes.
- The `mode' field provides nine bits specifying file permissions and
+ The 'mode' field provides nine bits specifying file permissions and
three bits to specify the Set UID, Set GID, and Save Text ("sticky")
modes. Values for these bits are defined above. When special
permissions are required to create a file with a given mode, and the
user restoring files from the archive does not hold such permissions,
-the mode bit(s) specifying those special permissions are ignored.
-Modes which are not supported by the operating system restoring files
-from the archive will be ignored. Unsupported modes should be faked up
-when creating or updating an archive; e.g., the group permission could
-be copied from the _other_ permission.
+the mode bit(s) specifying those special permissions are ignored. Modes
+which are not supported by the operating system restoring files from the
+archive will be ignored. Unsupported modes should be faked up when
+creating or updating an archive; e.g., the group permission could be
+copied from the _other_ permission.
- The `uid' and `gid' fields are the numeric user and group ID of the
+ The 'uid' and 'gid' fields are the numeric user and group ID of the
file owners, respectively. If the operating system does not support
numeric user or group IDs, these fields should be ignored.
- The `size' field is the size of the file in bytes; linked files are
+ The 'size' field is the size of the file in bytes; linked files are
archived with this field specified as zero.
- The `mtime' field is the data modification time of the file at the
-time it was archived. It is the ASCII representation of the octal
-value of the last time the file's contents were modified, represented
-as an integer number of seconds since January 1, 1970, 00:00
-Coordinated Universal Time.
+ The 'mtime' field is the data modification time of the file at the
+time it was archived. It is the ASCII representation of the octal value
+of the last time the file's contents were modified, represented as an
+integer number of seconds since January 1, 1970, 00:00 Coordinated
+Universal Time.
- The `chksum' field is the ASCII representation of the octal value of
-the simple sum of all bytes in the header block. Each 8-bit byte in
-the header is added to an unsigned integer, initialized to zero, the
+ The 'chksum' field is the ASCII representation of the octal value of
+the simple sum of all bytes in the header block. Each 8-bit byte in the
+header is added to an unsigned integer, initialized to zero, the
precision of which shall be no less than seventeen bits. When
-calculating the checksum, the `chksum' field is treated as if it were
+calculating the checksum, the 'chksum' field is treated as if it were
all blanks.
- The `typeflag' field specifies the type of file archived. If a
+ The 'typeflag' field specifies the type of file archived. If a
particular implementation does not recognize or permit the specified
type, the file will be extracted as if it were a regular file. As this
-action occurs, `tar' issues a warning to the standard error.
+action occurs, 'tar' issues a warning to the standard error.
- The `atime' and `ctime' fields are used in making incremental
+ The 'atime' and 'ctime' fields are used in making incremental
backups; they store, respectively, the particular file's access and
status change times.
- The `offset' is used by the `--multi-volume' (`-M') option, when
+ The 'offset' is used by the '--multi-volume' ('-M') option, when
making a multi-volume archive. The offset is number of bytes into the
file that we need to restart at to continue the file on the next tape,
i.e., where we store the location that a continued file is continued at.
- The following fields were added to deal with sparse files. A file
-is "sparse" if it takes in unallocated blocks which end up being
+ The following fields were added to deal with sparse files. A file is
+"sparse" if it takes in unallocated blocks which end up being
represented as zeros, i.e., no useful data. A test to see if a file is
sparse is to look at the number blocks allocated for it versus the
number of characters in the file; if there are fewer blocks allocated
for the file than would normally be allocated for a file of that size,
-then the file is sparse. This is the method `tar' uses to detect a
-sparse file, and once such a file is detected, it is treated
-differently from non-sparse files.
+then the file is sparse. This is the method 'tar' uses to detect a
+sparse file, and once such a file is detected, it is treated differently
+from non-sparse files.
- Sparse files are often `dbm' files, or other database-type files
+ Sparse files are often 'dbm' files, or other database-type files
which have data at some points and emptiness in the greater part of the
-file. Such files can appear to be very large when an `ls -l' is done
-on them, when in truth, there may be a very small amount of important
-data contained in the file. It is thus undesirable to have `tar' think
-that it must back up this entire file, as great quantities of room are
-wasted on empty blocks, which can lead to running out of room on a tape
-far earlier than is necessary. Thus, sparse files are dealt with so
-that these empty blocks are not written to the tape. Instead, what is
+file. Such files can appear to be very large when an 'ls -l' is done on
+them, when in truth, there may be a very small amount of important data
+contained in the file. It is thus undesirable to have 'tar' think that
+it must back up this entire file, as great quantities of room are wasted
+on empty blocks, which can lead to running out of room on a tape far
+earlier than is necessary. Thus, sparse files are dealt with so that
+these empty blocks are not written to the tape. Instead, what is
written to the tape is a description, of sorts, of the sparse file:
where the holes are, how big the holes are, and how much data is found
at the end of the hole. This way, the file takes up potentially far
look exactly the way it looked beforehand. The following is a
description of the fields used to handle a sparse file:
- The `sp' is an array of `struct sparse'. Each `struct sparse'
+ The 'sp' is an array of 'struct sparse'. Each 'struct sparse'
contains two 12-character strings which represent an offset into the
file and a number of bytes to be written at that offset. The offset is
absolute, and not relative to the offset in preceding array element.
- The header can hold four of these `struct sparse' at the moment; if
+ The header can hold four of these 'struct sparse' at the moment; if
more are needed, they are not stored in the header.
- The `isextended' flag is set when an `extended_header' is needed to
+ The 'isextended' flag is set when an 'extended_header' is needed to
deal with a file. Note that this means that this flag can only be set
when dealing with a sparse file, and it is only set in the event that
-the description of the file will not fit in the allotted room for
-sparse structures in the header. In other words, an extended_header is
-needed.
-
- The `extended_header' structure is used for sparse files which need
-more sparse structures than can fit in the header. The header can fit
-4 such structures; if more are needed, the flag `isextended' gets set
-and the next block is an `extended_header'.
-
- Each `extended_header' structure contains an array of 21 sparse
-structures, along with a similar `isextended' flag that the header had.
-There can be an indeterminate number of such `extended_header's to
+the description of the file will not fit in the allotted room for sparse
+structures in the header. In other words, an extended_header is needed.
+
+ The 'extended_header' structure is used for sparse files which need
+more sparse structures than can fit in the header. The header can fit 4
+such structures; if more are needed, the flag 'isextended' gets set and
+the next block is an 'extended_header'.
+
+ Each 'extended_header' structure contains an array of 21 sparse
+structures, along with a similar 'isextended' flag that the header had.
+There can be an indeterminate number of such 'extended_header's to
describe a sparse file.
-`REGTYPE'
-`AREGTYPE'
+'REGTYPE'
+'AREGTYPE'
These flags represent a regular file. In order to be compatible
- with older versions of `tar', a `typeflag' value of `AREGTYPE'
+ with older versions of 'tar', a 'typeflag' value of 'AREGTYPE'
should be silently recognized as a regular file. New archives
- should be created using `REGTYPE'. Also, for backward
- compatibility, `tar' treats a regular file whose name ends with a
+ should be created using 'REGTYPE'. Also, for backward
+ compatibility, 'tar' treats a regular file whose name ends with a
slash as a directory.
-`LNKTYPE'
+'LNKTYPE'
This flag represents a file linked to another file, of any type,
previously archived. Such files are identified in Unix by each
file having the same device and inode number. The linked-to name
- is specified in the `linkname' field with a trailing null.
+ is specified in the 'linkname' field with a trailing null.
-`SYMTYPE'
+'SYMTYPE'
This represents a symbolic link to another file. The linked-to
- name is specified in the `linkname' field with a trailing null.
+ name is specified in the 'linkname' field with a trailing null.
-`CHRTYPE'
-`BLKTYPE'
+'CHRTYPE'
+'BLKTYPE'
These represent character special files and block special files
- respectively. In this case the `devmajor' and `devminor' fields
+ respectively. In this case the 'devmajor' and 'devminor' fields
will contain the major and minor device numbers respectively.
Operating systems may map the device specifications to their own
local specification, or may ignore the entry.
-`DIRTYPE'
+'DIRTYPE'
This flag specifies a directory or sub-directory. The directory
- name in the `name' field should end with a slash. On systems where
- disk allocation is performed on a directory basis, the `size' field
+ name in the 'name' field should end with a slash. On systems where
+ disk allocation is performed on a directory basis, the 'size' field
will contain the maximum number of bytes (which may be rounded to
the nearest disk block allocation unit) which the directory may
- hold. A `size' field of zero indicates no such limiting. Systems
+ hold. A 'size' field of zero indicates no such limiting. Systems
which do not support limiting in this manner should ignore the
- `size' field.
+ 'size' field.
-`FIFOTYPE'
+'FIFOTYPE'
This specifies a FIFO special file. Note that the archiving of a
FIFO file archives the existence of this file and not its contents.
-`CONTTYPE'
+'CONTTYPE'
This specifies a contiguous file, which is the same as a normal
file except that, in operating systems which support it, all its
space is allocated contiguously on the disk. Operating systems
which do not allow contiguous allocation should silently treat this
type as a normal file.
-`A' ... `Z'
+'A' ... 'Z'
These are reserved for custom implementations. Some of these are
used in the GNU modified format, as described below.
-
Other values are reserved for specification in future revisions of
-the P1003 standard, and should not be used by any `tar' program.
+the P1003 standard, and should not be used by any 'tar' program.
- The `magic' field indicates that this archive was output in the
-P1003 archive format. If this field contains `TMAGIC', the `uname' and
-`gname' fields will contain the ASCII representation of the owner and
+ The 'magic' field indicates that this archive was output in the P1003
+archive format. If this field contains 'TMAGIC', the 'uname' and
+'gname' fields will contain the ASCII representation of the owner and
group of the file respectively. If found, the user and group IDs are
-used rather than the values in the `uid' and `gid' fields.
+used rather than the values in the 'uid' and 'gid' fields.
For references, see ISO/IEC 9945-1:1990 or IEEE Std 1003.1-1990,
-pages 169-173 (section 10.1) for `Archive/Interchange File Format'; and
+pages 169-173 (section 10.1) for 'Archive/Interchange File Format'; and
IEEE Std 1003.2-1992, pages 380-388 (section 4.48) and pages 936-940
-(section E.4.48) for `pax - Portable archive interchange'.
+(section E.4.48) for 'pax - Portable archive interchange'.
\1f
File: tar.info, Node: Extensions, Next: Sparse Formats, Prev: Standard, Up: Tar Internals
_(This message will disappear, once this node revised.)_
-The GNU format uses additional file types to describe new types of
+ The GNU format uses additional file types to describe new types of
files in an archive. These are listed below.
-`GNUTYPE_DUMPDIR'
-`'D''
+'GNUTYPE_DUMPDIR'
+''D''
This represents a directory and a list of files created by the
- `--incremental' (`-G') option. The `size' field gives the total
+ '--incremental' ('-G') option. The 'size' field gives the total
size of the associated list of files. Each file name is preceded
- by either a `Y' (the file should be in this archive) or an `N'.
+ by either a 'Y' (the file should be in this archive) or an 'N'.
(The file is a directory, or is not stored in the archive.) Each
file name is terminated by a null. There is an additional null
after the last file name.
-`GNUTYPE_MULTIVOL'
-`'M''
+'GNUTYPE_MULTIVOL'
+''M''
This represents a file continued from another volume of a
- multi-volume archive created with the `--multi-volume' (`-M')
+ multi-volume archive created with the '--multi-volume' ('-M')
option. The original type of the file is not given here. The
- `size' field gives the maximum size of this piece of the file
+ 'size' field gives the maximum size of this piece of the file
(assuming the volume does not end before the file is written out).
- The `offset' field gives the offset from the beginning of the file
- where this part of the file begins. Thus `size' plus `offset'
+ The 'offset' field gives the offset from the beginning of the file
+ where this part of the file begins. Thus 'size' plus 'offset'
should equal the original size of the file.
-`GNUTYPE_SPARSE'
-`'S''
+'GNUTYPE_SPARSE'
+''S''
This flag indicates that we are dealing with a sparse file. Note
that archiving a sparse file requires special operations to find
holes in the file, which mark the positions of these holes, along
with the number of bytes of data to be found after the hole.
-`GNUTYPE_VOLHDR'
-`'V''
+'GNUTYPE_VOLHDR'
+''V''
This file type is used to mark the volume header that was given
- with the `--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL') option when
- the archive was created. The `name' field contains the `name'
- given after the `--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL')
- option. The `size' field is zero. Only the first file in each
+ with the '--label=ARCHIVE-LABEL' ('-V ARCHIVE-LABEL') option when
+ the archive was created. The 'name' field contains the 'name'
+ given after the '--label=ARCHIVE-LABEL' ('-V ARCHIVE-LABEL')
+ option. The 'size' field is zero. Only the first file in each
volume of an archive should have this type.
-
- You may have trouble reading a GNU format archive on a non-GNU
-system if the options `--incremental' (`-G'), `--multi-volume' (`-M'),
-`--sparse' (`-S'), or `--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL') were
-used when writing the archive. In general, if `tar' does not use the
-GNU-added fields of the header, other versions of `tar' should be able
-to read the archive. Otherwise, the `tar' program will give an error,
+ You may have trouble reading a GNU format archive on a non-GNU system
+if the options '--incremental' ('-G'), '--multi-volume' ('-M'),
+'--sparse' ('-S'), or '--label=ARCHIVE-LABEL' ('-V ARCHIVE-LABEL') were
+used when writing the archive. In general, if 'tar' does not use the
+GNU-added fields of the header, other versions of 'tar' should be able
+to read the archive. Otherwise, the 'tar' program will give an error,
the most likely one being a checksum error.
\1f
Storing Sparse Files
====================
-The notion of sparse file, and the ways of handling it from the point
-of view of GNU `tar' user have been described in detail in *note
-sparse::. This chapter describes the internal format GNU `tar' uses to
-store such files.
+The notion of sparse file, and the ways of handling it from the point of
+view of GNU 'tar' user have been described in detail in *note sparse::.
+This chapter describes the internal format GNU 'tar' uses to store such
+files.
- The support for sparse files in GNU `tar' has a long history. The
+ The support for sparse files in GNU 'tar' has a long history. The
earliest version featuring this support that I was able to find was
1.09, released in November, 1990. The format introduced back then is
called "old GNU" sparse format and in spite of the fact that its design
-contained many flaws, it was the only format GNU `tar' supported until
+contained many flaws, it was the only format GNU 'tar' supported until
version 1.14 (May, 2004), which introduced initial support for sparse
-archives in PAX archives (*note posix::). This format was not free
-from design flaws, either and it was subsequently improved in versions
-1.15.2 (November, 2005) and 1.15.92 (June, 2006).
+archives in PAX archives (*note posix::). This format was not free from
+design flaws, either and it was subsequently improved in versions 1.15.2
+(November, 2005) and 1.15.92 (June, 2006).
- In addition to GNU sparse format, GNU `tar' is able to read and
-extract sparse files archived by `star'.
+ In addition to GNU sparse format, GNU 'tar' is able to read and
+extract sparse files archived by 'star'.
The following subsections describe each format in detail.
\1f
File: tar.info, Node: Old GNU Format, Next: PAX 0, Up: Sparse Formats
-D.0.1 Old GNU Format
---------------------
+Old GNU Format
+--------------
-The format introduced in November 1990 (v. 1.09) was designed on top of
-standard `ustar' headers in such an unfortunate way that some of its
+The format introduced in November 1990 (v. 1.09) was designed on top of
+standard 'ustar' headers in such an unfortunate way that some of its
fields overwrote fields required by POSIX.
- An old GNU sparse header is designated by type `S'
-(`GNUTYPE_SPARSE') and has the following layout:
+ An old GNU sparse header is designated by type 'S' ('GNUTYPE_SPARSE')
+and has the following layout:
Offset Size Name Data type Contents
-----------------------------------------------------------------------------
+----------------------------------------------------------------------------
0 345 N/A Not used.
-345 12 atime Number `atime' of the file.
-357 12 ctime Number `ctime' of the file .
+345 12 atime Number 'atime' of the file.
+357 12 ctime Number 'ctime' of the file .
369 12 offset Number For multivolume archives:
the offset of the start of
this volume.
381 4 N/A Not used.
385 1 N/A Not used.
-386 96 sp `sparse_header'(4 entries) File map.
-482 1 isextended Bool `1' if an extension sparse
- header follows, `0'
+386 96 sp 'sparse_header'(4 entries) File map.
+482 1 isextended Bool '1' if an extension sparse
+ header follows, '0'
otherwise.
483 12 realsize Number Real size of the file.
- Each of `sparse_header' object at offset 386 describes a single data
-chunk. It has the following structure:
+ Each of 'sparse_header' object at offset 386 describes a single data
+chunk. It has the following structure:
Offset Size Data type Contents
----------------------------------------------------------------------------
+---------------------------------------------------------------------------
0 12 Number Offset of the beginning of the chunk.
12 12 Number Size of the chunk.
- If the member contains more than four chunks, the `isextended' field
-of the header has the value `1' and the main header is followed by one
+ If the member contains more than four chunks, the 'isextended' field
+of the header has the value '1' and the main header is followed by one
or more "extension headers". Each such header has the following
structure:
Offset Size Name Data type Contents
-----------------------------------------------------------------------------
-0 21 sp `sparse_header' (21 entries) File map.
-504 1 isextended Bool `1' if an extension sparse
- header follows, or `0'
+----------------------------------------------------------------------------
+0 21 sp 'sparse_header'(21 entries) File map.
+504 1 isextended Bool '1' if an extension sparse
+ header follows, or '0'
otherwise.
- A header with `isextended=0' ends the map.
+ A header with 'isextended=0' ends the map.
\1f
File: tar.info, Node: PAX 0, Next: PAX 1, Prev: Old GNU Format, Up: Sparse Formats
-D.0.2 PAX Format, Versions 0.0 and 0.1
---------------------------------------
+PAX Format, Versions 0.0 and 0.1
+--------------------------------
-There are two formats available in this branch. The version `0.0' is
-the initial version of sparse format used by `tar' versions
-1.14-1.15.1. The sparse file map is kept in extended (`x') PAX header
-variables:
+There are two formats available in this branch. The version '0.0' is
+the initial version of sparse format used by 'tar' versions 1.14-1.15.1.
+The sparse file map is kept in extended ('x') PAX header variables:
-`GNU.sparse.size'
+'GNU.sparse.size'
Real size of the stored file;
-`GNU.sparse.numblocks'
+'GNU.sparse.numblocks'
Number of blocks in the sparse map;
-`GNU.sparse.offset'
+'GNU.sparse.offset'
Offset of the data block;
-`GNU.sparse.numbytes'
+'GNU.sparse.numbytes'
Size of the data block.
The latter two variables repeat for each data block, so the overall
1. Whereas the POSIX specification allows a variable to appear
multiple times in a header, it requires that only the last
occurrence be meaningful. Thus, multiple occurrences of
- `GNU.sparse.offset' and `GNU.sparse.numbytes' are conflicting with
+ 'GNU.sparse.offset' and 'GNU.sparse.numbytes' are conflicting with
the POSIX specs.
- 2. Attempting to extract such archives using a third-party's `tar'
+ 2. Attempting to extract such archives using a third-party's 'tar'
results in extraction of sparse files in _condensed form_. If the
- `tar' implementation in question does not support POSIX format, it
+ 'tar' implementation in question does not support POSIX format, it
will also extract a file containing extension header attributes.
This file can be used to expand the file to its original state.
- However, posix-aware `tar's will usually ignore the unknown
+ However, posix-aware 'tar's will usually ignore the unknown
variables, which makes restoring the file more difficult. *Note
Extraction of sparse members in v.0.0 format: extracting sparse
v.0.x, for the detailed description of how to restore such members
- using non-GNU `tar's.
+ using non-GNU 'tar's.
- GNU `tar' 1.15.2 introduced sparse format version `0.1', which
+ GNU 'tar' 1.15.2 introduced sparse format version '0.1', which
attempted to solve these problems. As its predecessor, this format
stores sparse map in the extended POSIX header. It retains
-`GNU.sparse.size' and `GNU.sparse.numblocks' variables, but instead of
-`GNU.sparse.offset'/`GNU.sparse.numbytes' pairs it uses a single
+'GNU.sparse.size' and 'GNU.sparse.numblocks' variables, but instead of
+'GNU.sparse.offset'/'GNU.sparse.numbytes' pairs it uses a single
variable:
-`GNU.sparse.map'
+'GNU.sparse.map'
Map of non-null data chunks. It is a string consisting of
comma-separated values "OFFSET,SIZE[,OFFSET-1,SIZE-1...]"
- To address the 2nd problem, the `name' field in `ustar' is replaced
+ To address the 2nd problem, the 'name' field in 'ustar' is replaced
with a special name, constructed using the following pattern:
%d/GNUSparseFile.%p/%f
The real name of the sparse file is stored in the variable
-`GNU.sparse.name'. Thus, those `tar' implementations that are not
-aware of GNU extensions will at least extract the files into separate
+'GNU.sparse.name'. Thus, those 'tar' implementations that are not aware
+of GNU extensions will at least extract the files into separate
directories, giving the user a possibility to expand it afterwards.
*Note Extraction of sparse members in v.0.1 format: extracting sparse
-v.0.x, for the detailed description of how to restore such members
-using non-GNU `tar's.
+v.0.x, for the detailed description of how to restore such members using
+non-GNU 'tar's.
- The resulting `GNU.sparse.map' string can be _very_ long. Although
-POSIX does not impose any limit on the length of a `x' header variable,
-this possibly can confuse some `tar's.
+ The resulting 'GNU.sparse.map' string can be _very_ long. Although
+POSIX does not impose any limit on the length of a 'x' header variable,
+this possibly can confuse some 'tar's.
\1f
File: tar.info, Node: PAX 1, Prev: PAX 0, Up: Sparse Formats
-D.0.3 PAX Format, Version 1.0
------------------------------
+PAX Format, Version 1.0
+-----------------------
-The version `1.0' of sparse format was introduced with GNU `tar'
+The version '1.0' of sparse format was introduced with GNU 'tar'
1.15.92. Its main objective was to make the resulting file extractable
-with little effort even by non-posix aware `tar' implementations.
+with little effort even by non-posix aware 'tar' implementations.
Starting from this version, the extended header preceding a sparse
member always contains the following variables that identify the format
being used:
-`GNU.sparse.major'
+'GNU.sparse.major'
Major version
-`GNU.sparse.minor'
+'GNU.sparse.minor'
Minor version
- The `name' field in `ustar' header contains a special name,
+ The 'name' field in 'ustar' header contains a special name,
constructed using the following pattern:
%d/GNUSparseFile.%p/%f
The real name of the sparse file is stored in the variable
-`GNU.sparse.name'. The real size of the file is stored in the variable
-`GNU.sparse.realsize'.
+'GNU.sparse.name'. The real size of the file is stored in the variable
+'GNU.sparse.realsize'.
- The sparse map itself is stored in the file data block, preceding
-the actual file data. It consists of a series of octal numbers of
-arbitrary length, delimited by newlines. The map is padded with nulls
-to the nearest block boundary.
+ The sparse map itself is stored in the file data block, preceding the
+actual file data. It consists of a series of octal numbers of arbitrary
+length, delimited by newlines. The map is padded with nulls to the
+nearest block boundary.
- The first number gives the number of entries in the map. Following
+ The first number gives the number of entries in the map. Following
are map entries, each one consisting of two numbers giving the offset
and size of the data block it describes.
- The format is designed in such a way that non-posix aware `tar's and
-`tar's not supporting `GNU.sparse.*' keywords will extract each sparse
+ The format is designed in such a way that non-posix aware 'tar's and
+'tar's not supporting 'GNU.sparse.*' keywords will extract each sparse
file in its condensed form with the file map prepended and will place it
into a separate directory. Then, using a simple program it would be
-possible to expand the file to its original form even without GNU `tar'.
+possible to expand the file to its original form even without GNU 'tar'.
*Note Sparse Recovery::, for the detailed information on how to extract
-sparse members without GNU `tar'.
+sparse members without GNU 'tar'.
\1f
File: tar.info, Node: Snapshot Files, Next: Dumpdir, Prev: Sparse Formats, Up: Tar Internals
========================================
A "snapshot file" (or "directory file") is created during incremental
-backups (*note Incremental Dumps::). It contains the status of the
-file system at the time of the dump and is used to determine which
-files were modified since the last backup.
+backups (*note Incremental Dumps::). It contains the status of the file
+system at the time of the dump and is used to determine which files were
+modified since the last backup.
- GNU `tar' version 1.28 supports three snapshot file formats. The
-first format, called "format 0", is the one used by GNU `tar' versions
-up to and including 1.15.1. The second format, called "format 1" is an
+ GNU 'tar' version 1.29 supports three snapshot file formats. The
+first format, called "format 0", is the one used by GNU 'tar' versions
+up to and including 1.15.1. The second format, called "format 1" is an
extended version of this format, that contains more metadata and allows
-for further extensions. It was used by alpha release version 1.15.90.
+for further extensions. It was used by alpha release version 1.15.90.
For alpha version 1.15.91 and stable releases version 1.16 up through
-1.28, the "format 2" is used.
+1.29, the "format 2" is used.
- GNU `tar' is able to read all three formats, but will create
+ GNU 'tar' is able to read all three formats, but will create
snapshots only in format 2.
This appendix describes all three formats in detail.
- 0. `Format 0' snapshot file begins with a line containing a decimal
+ 0. 'Format 0' snapshot file begins with a line containing a decimal
number that represents a UNIX timestamp of the beginning of the
- last archivation. This line is followed by directory metadata
- descriptions, one per line. Each description has the following
+ last archivation. This line is followed by directory metadata
+ descriptions, one per line. Each description has the following
format:
[NFS]DEV INODE NAME
where:
- NFS
- A single plus character (`+'), if this directory is located on
+ NFS
+ A single plus character ('+'), if this directory is located on
an NFS-mounted partition, otherwise empty.
(That is, for non-NFS directories, the first character on the
description line contains the start of the DEV field.)
- DEV
+ DEV
Device number of the directory;
- INODE
+ INODE
I-node number of the directory;
- NAME
- Name of the directory. Any special characters (white-space,
- backslashes, etc.) are quoted.
+ NAME
+ Name of the directory. Any special characters (white-space,
+ backslashes, etc.) are quoted.
- 1. `Format 1' snapshot file begins with a line specifying the
- format of the file. This line has the following structure:
+ 1. 'Format 1' snapshot file begins with a line specifying the format
+ of the file. This line has the following structure:
- `GNU tar-'TAR-VERSION`-'INCR-FORMAT-VERSION
+ 'GNU tar-'TAR-VERSION'-'INCR-FORMAT-VERSION
- where TAR-VERSION is the version number of GNU `tar'
- implementation that created this snapshot, and INCR-FORMAT-VERSION
- is the version number of the snapshot format (in this case `1').
+ where TAR-VERSION is the version number of GNU 'tar' implementation
+ that created this snapshot, and INCR-FORMAT-VERSION is the version
+ number of the snapshot format (in this case '1').
Next line contains two decimal numbers, representing the time of
- the last backup. First number is the number of seconds, the second
+ the last backup. First number is the number of seconds, the second
one is the number of nanoseconds, since the beginning of the epoch.
Lines that follow contain directory metadata, one line per
- directory. Each line is formatted as follows:
+ directory. Each line is formatted as follows:
[NFS]MTIME-SEC MTIME-NSEC DEV INODE NAME
where MTIME-SEC and MTIME-NSEC represent last modification time of
this directory with nanosecond precision; NFS, DEV, INODE and NAME
- have the same meaning as with `format 0'.
+ have the same meaning as with 'format 0'.
- 2. `Format 2' snapshot file begins with a format identifier, as
+ 2. 'Format 2' snapshot file begins with a format identifier, as
described for version 1, e.g.:
- GNU tar-1.28-2
+ GNU tar-1.29-2
- This line is followed by newline. Rest of file consists of
- records, separated by null (ASCII 0) characters. Thus, in contrast
+ This line is followed by newline. Rest of file consists of
+ records, separated by null (ASCII 0) characters. Thus, in contrast
to the previous formats, format 2 snapshot is a binary file.
First two records are decimal integers, representing the time of
- the last backup. First number is the number of seconds, the
- second one is the number of nanoseconds, since the beginning of the
- epoch. These are followed by arbitrary number of directory
- records.
+ the last backup. First number is the number of seconds, the second
+ one is the number of nanoseconds, since the beginning of the epoch.
+ These are followed by arbitrary number of directory records.
Each "directory record" contains a set of metadata describing a
particular directory. Parts of a directory record are delimited
with ASCII 0 characters. The following table describes each part.
The "Number" type in this table stands for a decimal integer in
- ASCII notation. (Negative values are preceeded with a "-"
+ ASCII notation. (Negative values are preceded with a "-"
character, while positive values have no leading punctuation.)
- Field Type Description
- ----------------------------------------------------------------------
- nfs Character `1' if the directory is located on an
- NFS-mounted partition, or `0' otherwise;
- timestamp_sec Number Modification time, seconds;
- timestamp_nsec Number Modification time, nanoseconds;
- dev Number Device number;
- ino Number I-node number;
- name String Directory name; in contrast to the
- previous versions it is not quoted;
- contents Dumpdir Contents of the directory; *Note
- Dumpdir::, for a description of its
- format.
-
+ Field Type Description
+ ---------------------------------------------------------------------------
+ nfs Character '1' if the directory is located on an
+ NFS-mounted partition, or '0' otherwise;
+ timestamp_sec Number Modification time, seconds;
+ timestamp_nsec Number Modification time, nanoseconds;
+ dev Number Device number;
+ ino Number I-node number;
+ name String Directory name; in contrast to the
+ previous versions it is not quoted;
+ contents Dumpdir Contents of the directory;
+ *Note Dumpdir::, for a description of its
+ format.
Dumpdirs stored in snapshot files contain only records of types
- `Y', `N' and `D'.
+ 'Y', 'N' and 'D'.
The specific range of values allowed in each of the "Number" fields
- depends on the underlying C datatypes as determined when `tar' is
+ depends on the underlying C datatypes as determined when 'tar' is
compiled. To see the specific ranges allowed for a particular
- `tar' binary, you can use the `--show-snapshot-field-ranges'
+ 'tar' binary, you can use the '--show-snapshot-field-ranges'
option:
$ tar --show-shapshot-field-ranges
(This example is from a GNU/Linux x86_64 system.)
-
\1f
File: tar.info, Node: Dumpdir, Prev: Snapshot Files, Up: Tar Internals
C FILENAME \0
where C is one of the "control codes" described below, FILENAME is the
-name of the file C operates upon, and `\0' represents a nul character
+name of the file C operates upon, and '\0' represents a nul character
(ASCII 0). The white space characters were added for readability, real
dumpdirs do not contain them.
The following table describes control codes and their meanings:
-`Y'
+'Y'
FILENAME is contained in the archive.
-`N'
+'N'
FILENAME was present in the directory at the time the archive was
made, yet it was not dumped to the archive, because it had not
changed since the last backup.
-`D'
+'D'
FILENAME is a directory.
-`R'
+'R'
This code requests renaming of the FILENAME to the name specified
- with the `T' command, that immediately follows it.
+ with the 'T' command, that immediately follows it.
-`T'
- Specify target file name for `R' command (see below).
+'T'
+ Specify target file name for 'R' command (see below).
-`X'
+'X'
Specify "temporary directory" name for a rename operation (see
below).
- Codes `Y', `N' and `D' require FILENAME argument to be a relative
-file name to the directory this dumpdir describes, whereas codes `R',
-`T' and `X' require their argument to be an absolute file name.
+ Codes 'Y', 'N' and 'D' require FILENAME argument to be a relative
+file name to the directory this dumpdir describes, whereas codes 'R',
+'T' and 'X' require their argument to be an absolute file name.
- The three codes `R', `T' and `X' specify a "renaming operation". In
+ The three codes 'R', 'T' and 'X' specify a "renaming operation". In
the simplest case it is:
- R`source'\0T`dest'\0
+ Rsource\0Tdest\0
-which means "rename file `source' to file `dest'".
+which means "rename file 'source' to file 'dest'".
However, there are cases that require using a "temporary directory".
For example, consider the following scenario:
- 1. Previous run dumped a directory `foo' which contained the
- following three directories:
+ 1. Previous run dumped a directory 'foo' which contained the following
+ three directories:
a
b
2. They were renamed _cyclically_, so that:
- `a' became `b'
- `b' became `c'
- `c' became `a'
+ a became b
+ b became c
+ c became a
3. New incremental dump was made.
This case cannot be handled by three successive renames, since
-renaming `a' to `b' will destroy the existing directory. To correctly
-process it, GNU `tar' needs a temporary directory, so it creates the
+renaming 'a' to 'b' will destroy the existing directory. To correctly
+process it, GNU 'tar' needs a temporary directory, so it creates the
following dumpdir (newlines have been added for readability):
Xfoo\0
Rfoo/c\0Tfoo/a\0
R\0Tfoo/a\0
- The first command, `Xfoo\0', instructs the extractor to create a
-temporary directory in the directory `foo'. Second command,
-`Rfoo/aT\0', says "rename file `foo/a' to the temporary directory that
+ The first command, 'Xfoo\0', instructs the extractor to create a
+temporary directory in the directory 'foo'. Second command,
+'Rfoo/aT\0', says "rename file 'foo/a' to the temporary directory that
has just been created" (empty file name after a command means use
temporary directory). Third and fourth commands work as usual, and,
-finally, the last command, `R\0Tfoo/a\0' tells tar to rename the
-temporary directory to `foo/a'.
+finally, the last command, 'R\0Tfoo/a\0' tells tar to rename the
+temporary directory to 'foo/a'.
The exact placement of a dumpdir in the archive depends on the
archive format (*note Formats::):
* PAX archives
In PAX archives, dumpdir is stored in the extended header of the
- corresponding directory, in variable `GNU.dumpdir'.
+ corresponding directory, in variable 'GNU.dumpdir'.
* GNU and old GNU archives
- These formats implement special header type `D', which is similar
- to ustar header `5' (directory), except that it precedes a data
+ These formats implement special header type 'D', which is similar
+ to ustar header '5' (directory), except that it precedes a data
block containing the dumpdir.
\1f
Appendix E Genfile
******************
-This appendix describes `genfile', an auxiliary program used in the GNU
-tar testsuite. If you are not interested in developing GNU tar, skip
+This appendix describes 'genfile', an auxiliary program used in the GNU
+tar testsuite. If you are not interested in developing GNU tar, skip
this appendix.
- Initially, `genfile' was used to generate data files for the
-testsuite, hence its name. However, new operation modes were being
-implemented as the testsuite grew more sophisticated, and now `genfile'
+ Initially, 'genfile' was used to generate data files for the
+testsuite, hence its name. However, new operation modes were being
+implemented as the testsuite grew more sophisticated, and now 'genfile'
is a multi-purpose instrument.
There are three basic operation modes:
File Generation
- This is the default mode. In this mode, `genfile' generates data
+ This is the default mode. In this mode, 'genfile' generates data
files.
File Status
- In this mode `genfile' displays status of specified files.
+ In this mode 'genfile' displays status of specified files.
Synchronous Execution.
- In this mode `genfile' executes the given program with
- `--checkpoint' option and executes a set of actions when specified
+ In this mode 'genfile' executes the given program with
+ '--checkpoint' option and executes a set of actions when specified
checkpoints are reached.
* Menu:
E.1 Generate Mode
=================
-In this mode `genfile' creates a data file for the test suite. The size
-of the file is given with the `--length' (`-l') option. By default the
+In this mode 'genfile' creates a data file for the test suite. The size
+of the file is given with the '--length' ('-l') option. By default the
file contents is written to the standard output, this can be changed
-using `--file' (`-f') command line option. Thus, the following two
+using '--file' ('-f') command line option. Thus, the following two
commands are equivalent:
genfile --length 100 > outfile
genfile --length 100 --file outfile
- If `--length' is not given, `genfile' will generate an empty
+ If '--length' is not given, 'genfile' will generate an empty
(zero-length) file.
- The command line option `--seek=N' istructs `genfile' to skip the
+ The command line option '--seek=N' istructs 'genfile' to skip the
given number of bytes (N) in the output file before writing to it. It
-is similar to the `seek=N' of the `dd' utility.
+is similar to the 'seek=N' of the 'dd' utility.
- You can instruct `genfile' to create several files at one go, by
-giving it `--files-from' (`-T') option followed by a name of file
-containing a list of file names. Using dash (`-') instead of the file
-name causes `genfile' to read file list from the standard input. For
+ You can instruct 'genfile' to create several files at one go, by
+giving it '--files-from' ('-T') option followed by a name of file
+containing a list of file names. Using dash ('-') instead of the file
+name causes 'genfile' to read file list from the standard input. For
example:
- # Read file names from file `file.list'
+ # Read file names from file file.list
genfile --files-from file.list
# Read file names from standard input
genfile --files-from -
- The list file is supposed to contain one file name per line. To use
-file lists separated by ASCII NUL character, use `--null' (`-0')
-command line option:
+ The list file is supposed to contain one file name per line. To use
+file lists separated by ASCII NUL character, use '--null' ('-0') command
+line option:
genfile --null --files-from file.list
The default data pattern for filling the generated file consists of
first 256 letters of ASCII code, repeated enough times to fill the
-entire file. This behavior can be changed with `--pattern' option. This
-option takes a mandatory argument, specifying pattern name to use.
+entire file. This behavior can be changed with '--pattern' option.
+This option takes a mandatory argument, specifying pattern name to use.
Currently two patterns are implemented:
-`--pattern=default'
+'--pattern=default'
The default pattern as described above.
-`--pattern=zero'
+'--pattern=zero'
Fills the file with zeroes.
- If no file name was given, the program exits with the code `0'.
-Otherwise, it exits with `0' only if it was able to create a file of
-the specified length.
+ If no file name was given, the program exits with the code '0'.
+Otherwise, it exits with '0' only if it was able to create a file of the
+specified length.
- Special option `--sparse' (`-s') instructs `genfile' to create a
-sparse file. Sparse files consist of "data fragments", separated by
-"holes" or blocks of zeros. On many operating systems, actual disk
+ Special option '--sparse' ('-s') instructs 'genfile' to create a
+sparse file. Sparse files consist of "data fragments", separated by
+"holes" or blocks of zeros. On many operating systems, actual disk
storage is not allocated for holes, but they are counted in the length
-of the file. To create a sparse file, `genfile' should know where to
-put data fragments, and what data to use to fill them. So, when
-`--sparse' is given the rest of the command line specifies a so-called
+of the file. To create a sparse file, 'genfile' should know where to
+put data fragments, and what data to use to fill them. So, when
+'--sparse' is given the rest of the command line specifies a so-called
"file map".
- The file map consists of any number of "fragment descriptors". Each
+ The file map consists of any number of "fragment descriptors". Each
descriptor is composed of two values: a number, specifying fragment
offset from the end of the previous fragment or, for the very first
-fragment, from the beginning of the file, and "contents string", i.e.,
-a string of characters, specifying the pattern to fill the fragment
-with. File offset can be suffixed with the following quantifiers:
+fragment, from the beginning of the file, and "contents string", that
+specifies the pattern to fill the fragment with. File offset can be
+suffixed with the following quantifiers:
-`k'
-`K'
+'k'
+'K'
The number is expressed in kilobytes.
-
-`m'
-`M'
+'m'
+'M'
The number is expressed in megabytes.
-
-`g'
-`G'
+'g'
+'G'
The number is expressed in gigabytes.
- For each letter in contents string `genfile' will generate a "block"
-of data, filled with this letter and will write it to the fragment. The
-size of block is given by `--block-size' option. It defaults to 512.
-Thus, if the string consists of N characters, the resulting file
-fragment will contain `N*BLOCK-SIZE' of data.
-
- Last fragment descriptor can have only file offset part. In this
-case `genfile' will create a hole at the end of the file up to the
-given offset.
+ Contents string can be either a fragment size or a pattern. Fragment
+size is a decimal number, prefixed with an equals sign. It can be
+suffixed with a quantifier, as discussed above. If fragment size is
+given, the fragment of that size will be filled with the currently
+selected pattern (*note -pattern: Generate Mode.) and written to the
+file.
+
+ A pattern is a string of arbitrary ASCII characters. For each of
+them, 'genfile' will generate a "block" of data, filled with that
+character and will write it to the fragment. The size of block is given
+by '--block-size' option. It defaults to 512. Thus, if pattern
+consists of N characters, the resulting file fragment will contain
+'N*BLOCK-SIZE' bytes of data.
+
+ The last fragment descriptor can have only file offset part. In this
+case 'genfile' will create a hole at the end of the file up to the given
+offset.
+
+ A dash appearing as a fragment descriptor instructs 'genfile' to read
+file map from the standard input. Each line of input should consist of
+fragment offset and contents string, separated by any amount of
+whitespace.
For example, consider the following invocation:
Offset Length Contents
0 4*512=2048 Four 512-byte blocks, filled
- with letters `A', `B', `C' and
- `D'.
+ with letters 'A', 'B', 'C' and
+ 'D'.
2048 1046528 Zero bytes
-1050624 5*512=2560 Five blocks, filled with letters
- `E', `F', `G', `H', `I'.
+1050624 5*512=2560 Five blocks, filled with
+ letters 'E', 'F', 'G', 'H',
+ 'I'.
1053184 2048000 Zero bytes
- The exit code of `genfile --status' command is `0' only if created
-file is actually sparse.
+ The exit code of 'genfile --sparse' command is '0' only if created
+file is actually sparse. If it is not, the appropriate error message is
+displayed and the command exists with code '1'. The '--quite' ('-q')
+option suppresses this behavior. If '--quite' is given, 'genfile
+--sparse' exits with code '0' if it was able to create the file, whether
+the resulting file is sparse or not.
\1f
File: tar.info, Node: Status Mode, Next: Exec Mode, Prev: Generate Mode, Up: Genfile
E.2 Status Mode
===============
-In status mode, `genfile' prints file system status for each file
-specified in the command line. This mode is toggled by `--stat' (`-S')
-command line option. An optional argument to this option specifies
-output "format": a comma-separated list of `struct stat' fields to be
-displayed. This list can contain following identifiers:
+In status mode, 'genfile' prints file system status for each file
+specified in the command line. This mode is toggled by '--stat' ('-S')
+command line option. An optional argument to this option specifies
+output "format": a comma-separated list of 'struct stat' fields to be
+displayed. This list can contain following identifiers:
name
The file name.
mode[.NUMBER]
st_mode[.NUMBER]
+
File mode in octal. Optional NUMBER specifies octal mask to be
- applied to the mode before outputting. For example, `--stat
+ applied to the mode before outputting. For example, '--stat
mode.777' will preserve lower nine bits of it. Notice, that you
- can use any punctuation character in place of `.'.
+ can use any punctuation character in place of '.'.
nlink
st_nlink
Time of last status change
sparse
- A boolean value indicating whether the file is `sparse'.
+ A boolean value indicating whether the file is 'sparse'.
Modification times are displayed in UTC as UNIX timestamps, unless
-suffixed with `H' (for "human-readable"), as in `ctimeH', in which case
-usual `tar tv' output format is used.
+suffixed with 'H' (for "human-readable"), as in 'ctimeH', in which case
+usual 'tar tv' output format is used.
- The default output format is: `name,dev,ino,mode,
+ The default output format is: 'name,dev,ino,mode,
nlink,uid,gid,size,blksize,blocks,atime,mtime,ctime'.
For example, the following command will display file names and
E.3 Exec Mode
=============
-This mode is designed for testing the behavior of `paxutils' commands
-when some of the files change during archiving. It is an experimental
+This mode is designed for testing the behavior of 'paxutils' commands
+when some of the files change during archiving. It is an experimental
mode.
- The `Exec Mode' is toggled by `--run' command line option (or its
-alias `-r'). The non-optional arguments to `getopt' give the command
-line to be executed. Normally, it should contain at least the
-`--checkpoint' option.
+ The 'Exec Mode' is toggled by '--run' command line option (or its
+alias '-r'). The non-optional arguments to 'getopt' give the command
+line to be executed. Normally, it should contain at least the
+'--checkpoint' option.
A set of options is provided for defining checkpoint values and
-actions to be executed upon reaching them. Checkpoint values are
-introduced with the `--checkpoint' command line option. Argument to
+actions to be executed upon reaching them. Checkpoint values are
+introduced with the '--checkpoint' command line option. Argument to
this option is the number of checkpoint in decimal.
Any number of "actions" may be specified after a checkpoint.
Available actions are
-`--cut FILE'
-`--truncate FILE'
- Truncate FILE to the size specified by previous `--length' option
+'--cut FILE'
+'--truncate FILE'
+ Truncate FILE to the size specified by previous '--length' option
(or 0, if it is not given).
-`--append FILE'
- Append data to FILE. The size of data and its pattern are given by
- previous `--length' and `pattern' options.
+'--append FILE'
+ Append data to FILE. The size of data and its pattern are given by
+ previous '--length' and 'pattern' options.
-`--touch FILE'
- Update the access and modification times of FILE. These timestamps
- are changed to the current time, unless `--date' option was given,
- in which case they are changed to the specified time. Argument to
- `--date' option is a date specification in an almost arbitrary
+'--touch FILE'
+ Update the access and modification times of FILE. These timestamps
+ are changed to the current time, unless '--date' option was given,
+ in which case they are changed to the specified time. Argument to
+ '--date' option is a date specification in an almost arbitrary
format (*note Date input formats::).
-`--exec COMMAND'
+'--exec COMMAND'
Execute given shell command.
-`--unlink FILE'
+'--unlink FILE'
Unlink the FILE.
- Option `--verbose' instructs `genfile' to print on standard output
-notifications about checkpoints being executed and to verbosely
-describe exit status of the command.
+ Option '--verbose' instructs 'genfile' to print on standard output
+notifications about checkpoints being executed and to verbosely describe
+exit status of the command.
While the command is being executed its standard output remains
-connected to descriptor 1. All messages it prints to file descriptor 2,
+connected to descriptor 1. All messages it prints to file descriptor 2,
except checkpoint notifications, are forwarded to standard error.
- `Genfile' exits with the exit status of the executed command.
+ 'Genfile' exits with the exit status of the executed command.
- For compatibility with previous `genfile' versions, the `--run'
-option takes an optional argument. If used this way, its argument
-supplies the command line to be executed. There should be no
-non-optional arguments in the `genfile' command line.
+ For compatibility with previous 'genfile' versions, the '--run'
+option takes an optional argument. If used this way, its argument
+supplies the command line to be executed. There should be no
+non-optional arguments in the 'genfile' command line.
The actual command line is constructed by inserting the
-`--checkpoint' option between the command name and its first argument
-(if any). Due to this, the argument to `--run' may not use traditional
-`tar' option syntax, i.e., the following is wrong:
+'--checkpoint' option between the command name and its first argument
+(if any). Due to this, the argument to '--run' may not use traditional
+'tar' option syntax, i.e., the following is wrong:
# Wrong!
genfile --run='tar cf foo bar'
-Use the following syntax instead:
+ Use the following syntax instead:
genfile --run='tar -cf foo bar' ACTIONS...
Consider Perl, for instance. The tutorial manuals that people
normally use are non-free. How did this come about? Because the
authors of those manuals published them with restrictive terms--no
-copying, no modification, source files not available--which exclude
-them from the free software world.
+copying, no modification, source files not available--which exclude them
+from the free software world.
That wasn't the first time this sort of thing happened, and it was
-far from the last. Many times we have heard a GNU user eagerly
-describe a manual that he is writing, his intended contribution to the
-community, only to learn that he had ruined everything by signing a
-publication contract to make it non-free.
+far from the last. Many times we have heard a GNU user eagerly describe
+a manual that he is writing, his intended contribution to the community,
+only to learn that he had ruined everything by signing a publication
+contract to make it non-free.
Free documentation, like free software, is a matter of freedom, not
price. The problem with the non-free manual is not that publishers
modify. Non-free manuals do not allow this.
The criteria of freedom for a free manual are roughly the same as for
-free software. Redistribution (including the normal kinds of
-commercial redistribution) must be permitted, so that the manual can
-accompany every copy of the program, both on-line and on paper.
+free software. Redistribution (including the normal kinds of commercial
+redistribution) must be permitted, so that the manual can accompany
+every copy of the program, both on-line and on paper.
Permission for modification of the technical content is crucial too.
When people modify the software, adding or changing features, if they
changed version of the program is not really available to our community.
Some kinds of limits on the way modification is handled are
-acceptable. For example, requirements to preserve the original
-author's copyright notice, the distribution terms, or the list of
-authors, are ok. It is also no problem to require modified versions to
-include notice that they were modified. Even entire sections that may
-not be deleted or changed are acceptable, as long as they deal with
+acceptable. For example, requirements to preserve the original author's
+copyright notice, the distribution terms, or the list of authors, are
+ok. It is also no problem to require modified versions to include
+notice that they were modified. Even entire sections that may not be
+deleted or changed are acceptable, as long as they deal with
nontechnical topics (like this one). These kinds of restrictions are
-acceptable because they don't obstruct the community's normal use of
-the manual.
+acceptable because they don't obstruct the community's normal use of the
+manual.
- However, it must be possible to modify all the _technical_ content
-of the manual, and then distribute the result in all the usual media,
+ However, it must be possible to modify all the _technical_ content of
+the manual, and then distribute the result in all the usual media,
through all the usual channels. Otherwise, the restrictions obstruct
the use of the manual, it is not free, and we need another manual to
replace it.
Please spread the word about this issue. Our community continues to
-lose manuals to proprietary publishing. If we spread the word that
-free software needs free reference manuals and free tutorials, perhaps
-the next person who wants to contribute by writing documentation will
-realize, before it is too late, that only free manuals contribute to
-the free software community.
+lose manuals to proprietary publishing. If we spread the word that free
+software needs free reference manuals and free tutorials, perhaps the
+next person who wants to contribute by writing documentation will
+realize, before it is too late, that only free manuals contribute to the
+free software community.
If you are writing documentation, please insist on publishing it
under the GNU Free Documentation License or another free documentation
license. Remember that this decision requires your approval--you don't
-have to let the publisher decide. Some commercial publishers will use
-a free license if you insist, but they will not propose the option; it
-is up to you to raise the issue and say firmly that this is what you
-want. If the publisher you are dealing with refuses, please try other
+have to let the publisher decide. Some commercial publishers will use a
+free license if you insist, but they will not propose the option; it is
+up to you to raise the issue and say firmly that this is what you want.
+If the publisher you are dealing with refuses, please try other
publishers. If you're not sure whether a proposed license is free,
write to <licensing@gnu.org>.
The Free Software Foundation maintains a list of free documentation
published by other publishers, at
-`http://www.fsf.org/doc/other-free-books.html'.
+<http://www.fsf.org/doc/other-free-books.html>.
\1f
File: tar.info, Node: GNU Free Documentation License, Next: Index of Command Line Options, Prev: Free Software Needs Free Documentation, Up: Top
Version 1.3, 3 November 2008
- Copyright (C) 2000-2002, 2007-2008, 2014 Free Software
+ Copyright (C) 2000-2002, 2007-2008, 2014, 2016 Free Software
Foundation, Inc.
- `http://fsf.org/'
+ <http://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
free program should come with manuals providing the same freedoms
that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless
- of subject matter or whether it is published as a printed book.
- We recommend this License principally for works whose purpose is
+ of subject matter or whether it is published as a printed book. We
+ recommend this License principally for works whose purpose is
instruction or reference.
1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium,
- that contains a notice placed by the copyright holder saying it
- can be distributed under the terms of this License. Such a notice
+ that contains a notice placed by the copyright holder saying it can
+ be distributed under the terms of this License. Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The
"Document", below, refers to any such manual or work. Any member
- of the public is a licensee, and is addressed as "you". You
- accept the license if you copy, modify or distribute the work in a
- way requiring permission under copyright law.
+ of the public is a licensee, and is addressed as "you". You accept
+ the license if you copy, modify or distribute the work in a way
+ requiring permission under copyright law.
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
regarding them.
The "Invariant Sections" are certain Secondary Sections whose
- titles are designated, as being those of Invariant Sections, in
- the notice that says that the Document is released under this
- License. If a section does not fit the above definition of
- Secondary then it is not allowed to be designated as Invariant.
- The Document may contain zero Invariant Sections. If the Document
- does not identify any Invariant Sections then there are none.
+ titles are designated, as being those of Invariant Sections, in the
+ notice that says that the Document is released under this License.
+ If a section does not fit the above definition of Secondary then it
+ is not allowed to be designated as Invariant. The Document may
+ contain zero Invariant Sections. If the Document does not identify
+ any Invariant Sections then there are none.
The "Cover Texts" are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
- straightforwardly with generic text editors or (for images
- composed of pixels) generic paint programs or (for drawings) some
- widely available drawing editor, and that is suitable for input to
- text formatters or for automatic translation to a variety of
- formats suitable for input to text formatters. A copy made in an
- otherwise Transparent file format whose markup, or absence of
- markup, has been arranged to thwart or discourage subsequent
- modification by readers is not Transparent. An image format is
- not Transparent if used for any substantial amount of text. A
- copy that is not "Transparent" is called "Opaque".
+ straightforwardly with generic text editors or (for images composed
+ of pixels) generic paint programs or (for drawings) some widely
+ available drawing editor, and that is suitable for input to text
+ formatters or for automatic translation to a variety of formats
+ suitable for input to text formatters. A copy made in an otherwise
+ Transparent file format whose markup, or absence of markup, has
+ been arranged to thwart or discourage subsequent modification by
+ readers is not Transparent. An image format is not Transparent if
+ used for any substantial amount of text. A copy that is not
+ "Transparent" is called "Opaque".
Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format,
- SGML or XML using a publicly available DTD, and
- standard-conforming simple HTML, PostScript or PDF designed for
- human modification. Examples of transparent image formats include
- PNG, XCF and JPG. Opaque formats include proprietary formats that
- can be read and edited only by proprietary word processors, SGML or
- XML for which the DTD and/or processing tools are not generally
- available, and the machine-generated HTML, PostScript or PDF
- produced by some word processors for output purposes only.
+ SGML or XML using a publicly available DTD, and standard-conforming
+ simple HTML, PostScript or PDF designed for human modification.
+ Examples of transparent image formats include PNG, XCF and JPG.
+ Opaque formats include proprietary formats that can be read and
+ edited only by proprietary word processors, SGML or XML for which
+ the DTD and/or processing tools are not generally available, and
+ the machine-generated HTML, PostScript or PDF produced by some word
+ processors for output purposes only.
The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the
may not use technical measures to obstruct or control the reading
or further copying of the copies you make or distribute. However,
you may accept compensation in exchange for copies. If you
- distribute a large enough number of copies you must also follow
- the conditions in section 3.
+ distribute a large enough number of copies you must also follow the
+ conditions in section 3.
You may also lend copies, under the same conditions stated above,
and you may publicly display copies.
these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover. Both covers must also clearly
and legibly identify you as the publisher of these copies. The
- front cover must present the full title with all words of the
- title equally prominent and visible. You may add other material
- on the covers in addition. Copying with changes limited to the
- covers, as long as they preserve the title of the Document and
- satisfy these conditions, can be treated as verbatim copying in
- other respects.
+ front cover must present the full title with all words of the title
+ equally prominent and visible. You may add other material on the
+ covers in addition. Copying with changes limited to the covers, as
+ long as they preserve the title of the Document and satisfy these
+ conditions, can be treated as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
adjacent pages.
If you publish or distribute Opaque copies of the Document
- numbering more than 100, you must either include a
- machine-readable Transparent copy along with each Opaque copy, or
- state in or with each Opaque copy a computer-network location from
- which the general network-using public has access to download
- using public-standard network protocols a complete Transparent
- copy of the Document, free of added material. If you use the
- latter option, you must take reasonably prudent steps, when you
- begin distribution of Opaque copies in quantity, to ensure that
- this Transparent copy will remain thus accessible at the stated
- location until at least one year after the last time you
- distribute an Opaque copy (directly or through your agents or
- retailers) of that edition to the public.
+ numbering more than 100, you must either include a machine-readable
+ Transparent copy along with each Opaque copy, or state in or with
+ each Opaque copy a computer-network location from which the general
+ network-using public has access to download using public-standard
+ network protocols a complete Transparent copy of the Document, free
+ of added material. If you use the latter option, you must take
+ reasonably prudent steps, when you begin distribution of Opaque
+ copies in quantity, to ensure that this Transparent copy will
+ remain thus accessible at the stated location until at least one
+ year after the last time you distribute an Opaque copy (directly or
+ through your agents or retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of
- the Document well before redistributing any large number of
- copies, to give them a chance to provide you with an updated
- version of the Document.
+ the Document well before redistributing any large number of copies,
+ to give them a chance to provide you with an updated version of the
+ Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document
under the conditions of sections 2 and 3 above, provided that you
- release the Modified Version under precisely this License, with
- the Modified Version filling the role of the Document, thus
- licensing distribution and modification of the Modified Version to
- whoever possesses a copy of it. In addition, you must do these
- things in the Modified Version:
+ release the Modified Version under precisely this License, with the
+ Modified Version filling the role of the Document, thus licensing
+ distribution and modification of the Modified Version to whoever
+ possesses a copy of it. In addition, you must do these things in
+ the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title
- distinct from that of the Document, and from those of
- previous versions (which should, if there were any, be listed
- in the History section of the Document). You may use the
- same title as a previous version if the original publisher of
- that version gives permission.
+ distinct from that of the Document, and from those of previous
+ versions (which should, if there were any, be listed in the
+ History section of the Document). You may use the same title
+ as a previous version if the original publisher of that
+ version gives permission.
B. List on the Title Page, as authors, one or more persons or
entities responsible for authorship of the modifications in
I. Preserve the section Entitled "History", Preserve its Title,
and add to it an item stating at least the title, year, new
- authors, and publisher of the Modified Version as given on
- the Title Page. If there is no section Entitled "History" in
- the Document, create one stating the title, year, authors,
- and publisher of the Document as given on its Title Page,
- then add an item describing the Modified Version as stated in
- the previous sentence.
+ authors, and publisher of the Modified Version as given on the
+ Title Page. If there is no section Entitled "History" in the
+ Document, create one stating the title, year, authors, and
+ publisher of the Document as given on its Title Page, then add
+ an item describing the Modified Version as stated in the
+ previous sentence.
J. Preserve the network location, if any, given in the Document
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
- previous versions it was based on. These may be placed in
- the "History" section. You may omit a network location for a
- work that was published at least four years before the
- Document itself, or if the original publisher of the version
- it refers to gives permission.
+ previous versions it was based on. These may be placed in the
+ "History" section. You may omit a network location for a work
+ that was published at least four years before the Document
+ itself, or if the original publisher of the version it refers
+ to gives permission.
K. For any section Entitled "Acknowledgements" or "Dedications",
- Preserve the Title of the section, and preserve in the
- section all the substance and tone of each of the contributor
+ Preserve the Title of the section, and preserve in the section
+ all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.
- L. Preserve all the Invariant Sections of the Document,
- unaltered in their text and in their titles. Section numbers
- or the equivalent are not considered part of the section
- titles.
+ L. Preserve all the Invariant Sections of the Document, unaltered
+ in their text and in their titles. Section numbers or the
+ equivalent are not considered part of the section titles.
M. Delete any section Entitled "Endorsements". Such a section
may not be included in the Modified Version.
If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no
- material copied from the Document, you may at your option
- designate some or all of these sections as invariant. To do this,
- add their titles to the list of Invariant Sections in the Modified
- Version's license notice. These titles must be distinct from any
- other section titles.
+ material copied from the Document, you may at your option designate
+ some or all of these sections as invariant. To do this, add their
+ titles to the list of Invariant Sections in the Modified Version's
+ license notice. These titles must be distinct from any other
+ section titles.
You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
definition of a standard.
You may add a passage of up to five words as a Front-Cover Text,
- and a passage of up to 25 words as a Back-Cover Text, to the end
- of the list of Cover Texts in the Modified Version. Only one
- passage of Front-Cover Text and one of Back-Cover Text may be
- added by (or through arrangements made by) any one entity. If the
- Document already includes a cover text for the same cover,
- previously added by you or by arrangement made by the same entity
- you are acting on behalf of, you may not add another; but you may
- replace the old one, on explicit permission from the previous
- publisher that added the old one.
+ and a passage of up to 25 words as a Back-Cover Text, to the end of
+ the list of Cover Texts in the Modified Version. Only one passage
+ of Front-Cover Text and one of Back-Cover Text may be added by (or
+ through arrangements made by) any one entity. If the Document
+ already includes a cover text for the same cover, previously added
+ by you or by arrangement made by the same entity you are acting on
+ behalf of, you may not add another; but you may replace the old
+ one, on explicit permission from the previous publisher that added
+ the old one.
The author(s) and publisher(s) of the Document do not by this
License give permission to use their names for publicity for or to
You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
- modified versions, provided that you include in the combination
- all of the Invariant Sections of all of the original documents,
+ modified versions, provided that you include in the combination all
+ of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
- rules of this License for verbatim copying of each of the
- documents in all other respects.
+ rules of this License for verbatim copying of each of the documents
+ in all other respects.
You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
- a copy of this License into the extracted document, and follow
- this License in all other respects regarding verbatim copying of
- that document.
+ a copy of this License into the extracted document, and follow this
+ License in all other respects regarding verbatim copying of that
+ document.
7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other
- separate and independent documents or works, in or on a volume of
- a storage or distribution medium, is called an "aggregate" if the
+ separate and independent documents or works, in or on a volume of a
+ storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit. When the Document is included in an aggregate, this
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
- provisionally, unless and until the copyright holder explicitly
- and finally terminates your license, and (b) permanently, if the
+ provisionally, unless and until the copyright holder explicitly and
+ finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.
after your receipt of the notice.
Termination of your rights under this section does not terminate
- the licenses of parties who have received copies or rights from
- you under this License. If your rights have been terminated and
- not permanently reinstated, receipt of a copy of some or all of
- the same material does not give you any rights to use it.
+ the licenses of parties who have received copies or rights from you
+ under this License. If your rights have been terminated and not
+ permanently reinstated, receipt of a copy of some or all of the
+ same material does not give you any rights to use it.
- 10. FUTURE REVISIONS OF THIS LICENSE
+ 10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
- `http://www.gnu.org/copyleft/'.
+ <http://www.gnu.org/copyleft/>.
Each version of the License is given a distinguishing version
number. If the Document specifies that a particular numbered
version of this License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
- published (not as a draft) by the Free Software Foundation. If
- the Document does not specify a version number of this License,
- you may choose any version ever published (not as a draft) by the
- Free Software Foundation. If the Document specifies that a proxy
- can decide which future versions of this License can be used, that
+ published (not as a draft) by the Free Software Foundation. If the
+ Document does not specify a version number of this License, you may
+ choose any version ever published (not as a draft) by the Free
+ Software Foundation. If the Document specifies that a proxy can
+ decide which future versions of this License can be used, that
proxy's public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.
- 11. RELICENSING
+ 11. RELICENSING
"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
site under CC-BY-SA on the same site at any time before August 1,
2009, provided the MMC is eligible for relicensing.
-
ADDENDUM: How to use this License for your documents
====================================================
Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover
-Texts, replace the "with...Texts." line with this:
+Texts, replace the "with...Texts." line with this:
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
situation.
If your document contains nontrivial examples of program code, we
-recommend releasing these examples in parallel under your choice of
-free software license, such as the GNU General Public License, to
-permit their use in free software.
+recommend releasing these examples in parallel under your choice of free
+software license, such as the GNU General Public License, to permit
+their use in free software.
\1f
File: tar.info, Node: Index of Command Line Options, Next: Index, Prev: GNU Free Documentation License, Up: Top
Appendix H Index of Command Line Options
****************************************
-This appendix contains an index of all GNU `tar' long command line
-options. The options are listed without the preceding double-dash. For
+This appendix contains an index of all GNU 'tar' long command line
+options. The options are listed without the preceding double-dash. For
a cross-reference of short command line options, see *note Short Option
Summary::.
\0\b[index\0\b]
* Menu:
-* --keep-directory-symlink, summary: Option Summary. (line 377)
-* absolute-names: absolute. (line 10)
-* absolute-names, summary: Option Summary. (line 6)
-* add-file: files. (line 60)
-* after-date: after. (line 24)
-* after-date, summary: Option Summary. (line 13)
+* absolute-names: absolute. (line 10)
+* absolute-names, summary: Option Summary. (line 6)
+* acls, summary: Option Summary. (line 14)
+* add-file: files. (line 79)
+* after-date: after. (line 24)
+* after-date, summary: Option Summary. (line 17)
* anchored: controlling pattern-matching.
- (line 79)
-* anchored, summary: Option Summary. (line 16)
-* append <1>: appending files. (line 6)
-* append: append. (line 6)
-* append, summary: Operation Summary. (line 6)
-* atime-preserve: Attributes. (line 10)
-* atime-preserve, summary: Option Summary. (line 20)
-* auto-compress: gzip. (line 155)
-* auto-compress, summary: Option Summary. (line 66)
-* backup: backup. (line 41)
-* backup, summary: Option Summary. (line 72)
-* block-number: verbose. (line 115)
-* block-number, summary: Option Summary. (line 77)
-* blocking-factor: Blocking Factor. (line 8)
-* blocking-factor, summary: Option Summary. (line 83)
-* bzip2, summary: Option Summary. (line 88)
-* catenate: concatenate. (line 6)
-* catenate, summary: Operation Summary. (line 10)
-* check-device, described: Incremental Dumps. (line 108)
-* check-device, summary: Option Summary. (line 93)
-* check-links, described: hard links. (line 31)
-* check-links, summary: Option Summary. (line 144)
-* checkpoint: checkpoints. (line 6)
-* checkpoint, defined: checkpoints. (line 13)
-* checkpoint, summary: Option Summary. (line 98)
-* checkpoint-action: checkpoints. (line 6)
-* checkpoint-action, defined: checkpoints. (line 22)
-* checkpoint-action, summary: Option Summary. (line 106)
-* compare: compare. (line 6)
-* compare, summary: Operation Summary. (line 14)
-* compress: gzip. (line 113)
-* compress, summary: Option Summary. (line 153)
-* concatenate: concatenate. (line 6)
-* concatenate, summary: Operation Summary. (line 20)
-* confirmation, summary: Option Summary. (line 160)
-* create, additional options: create options. (line 6)
-* create, complementary notes: Basic tar. (line 11)
+ (line 78)
+* anchored, summary: Option Summary. (line 21)
+* append: append. (line 6)
+* append <1>: appending files. (line 6)
+* append, summary: Operation Summary. (line 6)
+* atime-preserve: Attributes. (line 10)
+* atime-preserve, summary: Option Summary. (line 25)
+* auto-compress: gzip. (line 150)
+* auto-compress, summary: Option Summary. (line 71)
+* backup: backup. (line 41)
+* backup, summary: Option Summary. (line 78)
+* block-number: verbose. (line 112)
+* block-number, summary: Option Summary. (line 84)
+* blocking-factor: Blocking Factor. (line 8)
+* blocking-factor, summary: Option Summary. (line 91)
+* bzip2, summary: Option Summary. (line 97)
+* catenate: concatenate. (line 6)
+* catenate, summary: Operation Summary. (line 11)
+* check-device, described: Incremental Dumps. (line 107)
+* check-device, summary: Option Summary. (line 103)
+* check-links, described: hard links. (line 31)
+* check-links, summary: Option Summary. (line 155)
+* checkpoint: checkpoints. (line 6)
+* checkpoint, defined: checkpoints. (line 13)
+* checkpoint, summary: Option Summary. (line 108)
+* checkpoint-action: checkpoints. (line 6)
+* checkpoint-action, defined: checkpoints. (line 22)
+* checkpoint-action, summary: Option Summary. (line 117)
+* clamp-mtime, summary: Option Summary. (line 172)
+* compare: compare. (line 6)
+* compare, summary: Operation Summary. (line 16)
+* compress: gzip. (line 113)
+* compress, summary: Option Summary. (line 164)
+* concatenate: concatenate. (line 6)
+* concatenate, summary: Operation Summary. (line 23)
+* confirmation, summary: Option Summary. (line 176)
+* create, additional options: create options. (line 6)
+* create, complementary notes: Basic tar. (line 11)
* create, introduced: Creating the archive.
- (line 6)
-* create, summary: Operation Summary. (line 25)
-* create, using with --verbose: create verbose. (line 6)
-* create, using with --verify: verify. (line 24)
+ (line 6)
+* create, summary: Operation Summary. (line 29)
+* create, using with '--verbose': create verbose. (line 6)
+* create, using with '--verify': verify. (line 24)
* delay-directory-restore: Directory Modification Times and Permissions.
- (line 62)
-* delay-directory-restore, summary: Option Summary. (line 163)
-* delete: delete. (line 6)
-* delete, summary: Operation Summary. (line 29)
-* delete, using before -append: append. (line 47)
-* dereference: dereference. (line 6)
-* dereference, summary: Option Summary. (line 168)
-* diff, summary: Operation Summary. (line 33)
-* directory: directory. (line 11)
-* directory, summary: Option Summary. (line 174)
-* exclude: exclude. (line 6)
+ (line 62)
+* delay-directory-restore, summary: Option Summary. (line 180)
+* delete: delete. (line 6)
+* delete, summary: Operation Summary. (line 34)
+* delete, using before -append: append. (line 47)
+* dereference: dereference. (line 6)
+* dereference, summary: Option Summary. (line 186)
+* diff, summary: Operation Summary. (line 39)
+* directory: directory. (line 11)
+* directory, summary: Option Summary. (line 193)
+* exclude: exclude. (line 6)
+* exclude <1>: exclude. (line 9)
* exclude, potential problems with: problems with exclude.
- (line 6)
-* exclude, summary: Option Summary. (line 181)
-* exclude-backups: exclude. (line 130)
-* exclude-backups, summary: Option Summary. (line 185)
-* exclude-caches: exclude. (line 153)
-* exclude-caches, summary: Option Summary. (line 193)
-* exclude-caches-all: exclude. (line 161)
-* exclude-caches-all, summary: Option Summary. (line 206)
-* exclude-caches-under: exclude. (line 157)
-* exclude-caches-under, summary: Option Summary. (line 200)
-* exclude-from: exclude. (line 6)
-* exclude-from, summary: Option Summary. (line 188)
-* exclude-ignore: exclude. (line 76)
-* exclude-ignore, summary: Option Summary. (line 210)
-* exclude-ignore-recursive: exclude. (line 81)
-* exclude-ignore-recursive, summary: Option Summary. (line 215)
-* exclude-tag: exclude. (line 170)
-* exclude-tag, summary: Option Summary. (line 220)
-* exclude-tag-all: exclude. (line 178)
-* exclude-tag-all, summary: Option Summary. (line 230)
-* exclude-tag-under: exclude. (line 174)
-* exclude-tag-under, summary: Option Summary. (line 225)
-* exclude-vcs: exclude. (line 85)
-* exclude-vcs, summary: Option Summary. (line 234)
-* exclude-vcs-ignores: exclude. (line 42)
-* exclude-vcs-ignores, summary: Option Summary. (line 240)
-* extract: extract. (line 6)
-* extract, additional options: extract options. (line 6)
-* extract, complementary notes: Basic tar. (line 48)
-* extract, summary: Operation Summary. (line 37)
-* extract, using with --listed-incremental: Incremental Dumps.
- (line 121)
-* file: file. (line 6)
-* file, short description: file. (line 15)
-* file, summary: Option Summary. (line 248)
-* file, tutorial: file tutorial. (line 6)
-* files-from: files. (line 14)
-* files-from, summary: Option Summary. (line 254)
-* force-local, short description: Device. (line 70)
-* force-local, summary: Option Summary. (line 260)
-* format, summary: Option Summary. (line 265)
-* full-time, summary: Option Summary. (line 290)
-* get, summary: Operation Summary. (line 42)
-* group: override. (line 88)
-* group, summary: Option Summary. (line 308)
-* gunzip, summary: Option Summary. (line 316)
-* gzip: gzip. (line 91)
-* gzip, summary: Option Summary. (line 316)
-* hard-dereference, described: hard links. (line 59)
-* hard-dereference, summary: Option Summary. (line 324)
-* help: help tutorial. (line 6)
-* help, introduction: help. (line 26)
-* help, summary: Option Summary. (line 330)
+ (line 6)
+* exclude, summary: Option Summary. (line 201)
+* exclude-backups: exclude. (line 114)
+* exclude-backups, summary: Option Summary. (line 206)
+* exclude-caches: exclude. (line 134)
+* exclude-caches, summary: Option Summary. (line 215)
+* exclude-caches-all: exclude. (line 142)
+* exclude-caches-all, summary: Option Summary. (line 230)
+* exclude-caches-under: exclude. (line 138)
+* exclude-caches-under, summary: Option Summary. (line 223)
+* exclude-from: exclude. (line 6)
+* exclude-from <1>: exclude. (line 20)
+* exclude-from, summary: Option Summary. (line 209)
+* exclude-ignore: exclude. (line 76)
+* exclude-ignore, summary: Option Summary. (line 235)
+* exclude-ignore-recursive: exclude. (line 81)
+* exclude-ignore-recursive, summary: Option Summary. (line 240)
+* exclude-tag: exclude. (line 151)
+* exclude-tag, summary: Option Summary. (line 245)
+* exclude-tag-all: exclude. (line 159)
+* exclude-tag-all, summary: Option Summary. (line 257)
+* exclude-tag-under: exclude. (line 155)
+* exclude-tag-under, summary: Option Summary. (line 251)
+* exclude-vcs: exclude. (line 85)
+* exclude-vcs, summary: Option Summary. (line 262)
+* exclude-vcs-ignores: exclude. (line 42)
+* exclude-vcs-ignores, summary: Option Summary. (line 269)
+* extract: extract. (line 6)
+* extract, additional options: extract options. (line 6)
+* extract, complementary notes: Basic tar. (line 49)
+* extract, summary: Operation Summary. (line 44)
+* extract, using with '--listed-incremental': Incremental Dumps.
+ (line 120)
+* file: file. (line 6)
+* file, short description: file. (line 15)
+* file, summary: Option Summary. (line 277)
+* file, tutorial: file tutorial. (line 6)
+* files-from: files. (line 14)
+* files-from, summary: Option Summary. (line 284)
+* force-local, short description: Device. (line 70)
+* force-local, summary: Option Summary. (line 291)
+* format, summary: Option Summary. (line 297)
+* full-time, summary: Option Summary. (line 322)
+* get, summary: Operation Summary. (line 50)
+* group: override. (line 99)
+* group, summary: Option Summary. (line 340)
+* group-map, summary: Option Summary. (line 350)
+* gunzip, summary: Option Summary. (line 360)
+* gzip: gzip. (line 91)
+* gzip, summary: Option Summary. (line 360)
+* hard-dereference, described: hard links. (line 59)
+* hard-dereference, summary: Option Summary. (line 369)
+* help: help tutorial. (line 6)
+* help, introduction: help. (line 26)
+* help, summary: Option Summary. (line 375)
+* hole-detection: sparse. (line 66)
+* hole-detection, summary: Option Summary. (line 381)
* ignore-case: controlling pattern-matching.
- (line 86)
-* ignore-case, summary: Option Summary. (line 335)
+ (line 85)
+* ignore-case, summary: Option Summary. (line 386)
* ignore-command-error: Writing to an External Program.
- (line 110)
-* ignore-command-error, summary: Option Summary. (line 339)
-* ignore-failed-read: Ignore Failed Read. (line 7)
-* ignore-failed-read, summary: Option Summary. (line 343)
-* ignore-zeros: Ignore Zeros. (line 6)
-* ignore-zeros, short description: Blocking Factor. (line 156)
-* ignore-zeros, summary: Option Summary. (line 347)
-* incremental, summary: Option Summary. (line 352)
-* incremental, using with --list: Incremental Dumps. (line 186)
-* index-file, summary: Option Summary. (line 359)
+ (line 111)
+* ignore-command-error, summary: Option Summary. (line 390)
+* ignore-failed-read: Ignore Failed Read. (line 7)
+* ignore-failed-read, summary: Option Summary. (line 394)
+* ignore-zeros: Ignore Zeros. (line 6)
+* ignore-zeros, short description: Blocking Factor. (line 152)
+* ignore-zeros, summary: Option Summary. (line 399)
+* incremental, summary: Option Summary. (line 405)
+* incremental, using with '--list': Incremental Dumps. (line 185)
+* index-file, summary: Option Summary. (line 413)
* info-script: Multi-Volume Archives.
- (line 88)
-* info-script, short description: Device. (line 122)
-* info-script, summary: Option Summary. (line 362)
-* interactive: interactive. (line 14)
-* interactive, summary: Option Summary. (line 370)
-* keep-newer-files: Keep Newer Files. (line 6)
-* keep-newer-files, summary: Option Summary. (line 390)
-* keep-old-files: Keep Old Files. (line 9)
+ (line 83)
+* info-script, short description: Device. (line 121)
+* info-script, summary: Option Summary. (line 417)
+* interactive: interactive. (line 14)
+* interactive, summary: Option Summary. (line 426)
+* keep-directory-symlink, summary: Option Summary. (line 434)
+* keep-newer-files: Keep Newer Files. (line 6)
+* keep-newer-files, summary: Option Summary. (line 448)
+* keep-old-files: Keep Old Files. (line 9)
* keep-old-files, introduced: Dealing with Old Files.
- (line 16)
-* keep-old-files, summary: Option Summary. (line 394)
-* label <1>: label. (line 6)
-* label: Tape Files. (line 6)
-* label, summary: Option Summary. (line 402)
-* level, described: Incremental Dumps. (line 76)
-* level, summary: Option Summary. (line 409)
-* list: list. (line 6)
-* list, summary: Operation Summary. (line 46)
-* list, using with --incremental: Incremental Dumps. (line 186)
-* list, using with --listed-incremental: Incremental Dumps. (line 186)
-* list, using with --verbose: list. (line 30)
-* list, using with file name arguments: list. (line 68)
-* listed-incremental, described: Incremental Dumps. (line 14)
-* listed-incremental, summary: Option Summary. (line 419)
-* listed-incremental, using with --extract: Incremental Dumps.
- (line 121)
-* listed-incremental, using with --list: Incremental Dumps. (line 186)
-* lzip: gzip. (line 104)
-* lzip, summary: Option Summary. (line 427)
-* lzma: gzip. (line 107)
-* lzma, summary: Option Summary. (line 431)
-* lzop: gzip. (line 110)
-* mode: override. (line 14)
-* mode, summary: Option Summary. (line 439)
-* mtime: override. (line 29)
-* mtime, summary: Option Summary. (line 445)
+ (line 16)
+* keep-old-files, summary: Option Summary. (line 453)
+* label: Tape Files. (line 6)
+* label <1>: label. (line 6)
+* label, summary: Option Summary. (line 462)
+* level, described: Incremental Dumps. (line 75)
+* level, summary: Option Summary. (line 470)
+* list: list. (line 6)
+* list, summary: Operation Summary. (line 55)
+* list, using with '--incremental': Incremental Dumps. (line 185)
+* list, using with '--listed-incremental': Incremental Dumps.
+ (line 185)
+* list, using with '--verbose': list. (line 34)
+* list, using with file name arguments: list. (line 25)
+* listed-incremental, described: Incremental Dumps. (line 14)
+* listed-incremental, summary: Option Summary. (line 480)
+* listed-incremental, using with '--extract': Incremental Dumps.
+ (line 120)
+* listed-incremental, using with '--list': Incremental Dumps.
+ (line 185)
+* lzip: gzip. (line 104)
+* lzip, summary: Option Summary. (line 489)
+* lzma: gzip. (line 107)
+* lzma, summary: Option Summary. (line 494)
+* lzop: gzip. (line 110)
+* mode: override. (line 14)
+* mode, summary: Option Summary. (line 504)
+* mtime: override. (line 30)
+* mtime, summary: Option Summary. (line 511)
* multi-volume: Multi-Volume Archives.
- (line 6)
-* multi-volume, short description: Device. (line 88)
-* multi-volume, summary: Option Summary. (line 454)
+ (line 6)
+* multi-volume, short description: Device. (line 88)
+* multi-volume, summary: Option Summary. (line 526)
* new-volume-script: Multi-Volume Archives.
- (line 88)
-* new-volume-script, short description: Device. (line 122)
-* new-volume-script, summary: Option Summary. (line 362)
-* newer: after. (line 24)
-* newer, summary: Option Summary. (line 462)
-* newer-mtime: after. (line 35)
-* newer-mtime, summary: Option Summary. (line 470)
+ (line 83)
+* new-volume-script, short description: Device. (line 121)
+* new-volume-script, summary: Option Summary. (line 417)
+* new-volume-script, summary <1>: Option Summary. (line 532)
+* newer: after. (line 24)
+* newer, summary: Option Summary. (line 536)
+* newer-mtime: after. (line 35)
+* newer-mtime, summary: Option Summary. (line 545)
+* no-acls, summary: Option Summary. (line 551)
* no-anchored: controlling pattern-matching.
- (line 79)
-* no-anchored, summary: Option Summary. (line 475)
-* no-auto-compress, summary: Option Summary. (line 479)
-* no-check-device, described: Incremental Dumps. (line 104)
-* no-check-device, summary: Option Summary. (line 483)
+ (line 78)
+* no-anchored, summary: Option Summary. (line 555)
+* no-auto-compress, summary: Option Summary. (line 559)
+* no-check-device, described: Incremental Dumps. (line 103)
+* no-check-device, summary: Option Summary. (line 564)
* no-delay-directory-restore: Directory Modification Times and Permissions.
- (line 68)
-* no-delay-directory-restore, summary: Option Summary. (line 488)
+ (line 68)
+* no-delay-directory-restore, summary: Option Summary. (line 569)
* no-ignore-case: controlling pattern-matching.
- (line 86)
-* no-ignore-case, summary: Option Summary. (line 494)
+ (line 85)
+* no-ignore-case, summary: Option Summary. (line 575)
* no-ignore-command-error: Writing to an External Program.
- (line 115)
-* no-ignore-command-error, summary: Option Summary. (line 497)
-* no-null, described: nul. (line 15)
-* no-null, summary: Option Summary. (line 501)
-* no-overwrite-dir, summary: Option Summary. (line 506)
-* no-quote-chars, summary: Option Summary. (line 510)
-* no-recursion: recurse. (line 11)
-* no-recursion, summary: Option Summary. (line 515)
-* no-same-owner: Attributes. (line 63)
-* no-same-owner, summary: Option Summary. (line 519)
-* no-same-permissions, summary: Option Summary. (line 525)
-* no-seek, summary: Option Summary. (line 530)
+ (line 116)
+* no-ignore-command-error, summary: Option Summary. (line 578)
+* no-null, described: nul. (line 15)
+* no-null, summary: Option Summary. (line 582)
+* no-overwrite-dir, summary: Option Summary. (line 588)
+* no-quote-chars, summary: Option Summary. (line 593)
+* no-recursion: recurse. (line 11)
+* no-recursion, summary: Option Summary. (line 598)
+* no-same-owner: Attributes. (line 63)
+* no-same-owner, summary: Option Summary. (line 603)
+* no-same-permissions, summary: Option Summary. (line 610)
+* no-seek, summary: Option Summary. (line 616)
+* no-selinux, summary: Option Summary. (line 622)
* no-unquote: Selecting Archive Members.
- (line 42)
-* no-unquote, summary: Option Summary. (line 535)
+ (line 42)
+* no-unquote, summary: Option Summary. (line 626)
+* no-verbatim-files-from: files. (line 75)
+* no-verbatim-files-from, summary: Option Summary. (line 630)
* no-wildcards: controlling pattern-matching.
- (line 41)
-* no-wildcards, summary: Option Summary. (line 539)
+ (line 41)
+* no-wildcards, summary: Option Summary. (line 644)
* no-wildcards-match-slash: controlling pattern-matching.
- (line 92)
-* no-wildcards-match-slash, summary: Option Summary. (line 542)
-* null, described: nul. (line 11)
-* null, summary: Option Summary. (line 545)
-* numeric-owner: Attributes. (line 69)
-* numeric-owner, summary: Option Summary. (line 551)
-* occurrence, described: append. (line 34)
-* occurrence, summary: Option Summary. (line 568)
-* old-archive, summary: Option Summary. (line 582)
-* one-file-system: one. (line 14)
-* one-file-system, summary: Option Summary. (line 585)
-* one-top-level, summary: Option Summary. (line 590)
-* overwrite: Overwrite Old Files. (line 6)
+ (line 91)
+* no-wildcards-match-slash, summary: Option Summary. (line 647)
+* no-xattrs, summary: Option Summary. (line 650)
+* null, described: nul. (line 11)
+* null, summary: Option Summary. (line 654)
+* numeric-owner: Attributes. (line 69)
+* numeric-owner, summary: Option Summary. (line 667)
+* occurrence, described: append. (line 34)
+* occurrence, summary: Option Summary. (line 685)
+* old-archive, summary: Option Summary. (line 700)
+* one-file-system: one. (line 14)
+* one-file-system, summary: Option Summary. (line 703)
+* one-top-level, summary: Option Summary. (line 708)
+* overwrite: Overwrite Old Files.
+ (line 6)
* overwrite, introduced: Dealing with Old Files.
- (line 32)
-* overwrite, summary: Option Summary. (line 601)
-* overwrite-dir: Overwrite Old Files. (line 28)
+ (line 32)
+* overwrite, summary: Option Summary. (line 719)
+* overwrite-dir: Overwrite Old Files.
+ (line 28)
* overwrite-dir, introduced: Dealing with Old Files.
- (line 6)
-* overwrite-dir, summary: Option Summary. (line 605)
-* owner: override. (line 57)
-* owner, summary: Option Summary. (line 609)
-* pax-option: PAX keywords. (line 6)
-* pax-option, summary: Option Summary. (line 617)
-* portability, summary: Option Summary. (line 623)
-* posix, summary: Option Summary. (line 627)
-* preserve: Attributes. (line 122)
-* preserve, summary: Option Summary. (line 630)
-* preserve-order: Same Order. (line 6)
-* preserve-order, summary: Option Summary. (line 634)
+ (line 6)
+* overwrite-dir, summary: Option Summary. (line 724)
+* owner: override. (line 67)
+* owner, summary: Option Summary. (line 729)
+* owner-map, summary: Option Summary. (line 739)
+* pax-option: PAX keywords. (line 6)
+* pax-option, summary: Option Summary. (line 749)
+* portability, summary: Option Summary. (line 755)
+* posix, summary: Option Summary. (line 759)
+* preserve-order: Same Order. (line 6)
+* preserve-order, summary: Option Summary. (line 762)
* preserve-permissions: Setting Access Permissions.
- (line 10)
-* preserve-permissions, short description: Attributes. (line 109)
-* preserve-permissions, summary: Option Summary. (line 637)
-* quote-chars, summary: Option Summary. (line 647)
-* quoting-style: quoting styles. (line 38)
-* quoting-style, summary: Option Summary. (line 651)
-* read-full-records <1>: read full records. (line 6)
-* read-full-records: Reading. (line 6)
-* read-full-records, short description: Blocking Factor. (line 172)
-* read-full-records, summary: Option Summary. (line 658)
-* record-size, summary: Option Summary. (line 663)
-* recursion: recurse. (line 22)
-* recursion, summary: Option Summary. (line 670)
-* recursive-unlink: Recursive Unlink. (line 6)
-* recursive-unlink, summary: Option Summary. (line 674)
-* remove-files: remove files. (line 6)
-* remove-files, summary: Option Summary. (line 679)
-* restrict, summary: Option Summary. (line 683)
-* rmt-command, summary: Option Summary. (line 688)
-* rsh-command: Device. (line 73)
-* rsh-command, summary: Option Summary. (line 692)
-* same-order: Same Order. (line 6)
-* same-order, summary: Option Summary. (line 696)
-* same-owner: Attributes. (line 44)
-* same-owner, summary: Option Summary. (line 704)
+ (line 10)
+* preserve-permissions, short description: Attributes. (line 109)
+* preserve-permissions, summary: Option Summary. (line 766)
+* quote-chars, summary: Option Summary. (line 777)
+* quoting-style: quoting styles. (line 38)
+* quoting-style, summary: Option Summary. (line 781)
+* read-full-records: Reading. (line 6)
+* read-full-records <1>: read full records. (line 6)
+* read-full-records, short description: Blocking Factor. (line 168)
+* read-full-records, summary: Option Summary. (line 788)
+* record-size, summary: Option Summary. (line 794)
+* recursion: recurse. (line 22)
+* recursion, summary: Option Summary. (line 802)
+* recursive-unlink: Recursive Unlink. (line 6)
+* recursive-unlink, summary: Option Summary. (line 807)
+* remove-files: remove files. (line 6)
+* remove-files, summary: Option Summary. (line 812)
+* restrict, summary: Option Summary. (line 817)
+* rmt-command, summary: Option Summary. (line 823)
+* rsh-command: Device. (line 73)
+* rsh-command, summary: Option Summary. (line 828)
+* same-order: Same Order. (line 6)
+* same-order, summary: Option Summary. (line 833)
+* same-owner: Attributes. (line 44)
+* same-owner, summary: Option Summary. (line 842)
* same-permissions: Setting Access Permissions.
- (line 10)
-* same-permissions, short description: Attributes. (line 109)
-* same-permissions, summary: Option Summary. (line 637)
-* seek, summary: Option Summary. (line 713)
-* show-defaults: defaults. (line 6)
-* show-defaults, summary: Option Summary. (line 722)
-* show-omitted-dirs: verbose. (line 107)
-* show-omitted-dirs, summary: Option Summary. (line 734)
-* show-snapshot-field-ranges: Snapshot Files. (line 113)
-* show-snapshot-field-ranges, summary: Option Summary. (line 738)
-* show-stored-names: list. (line 60)
-* show-stored-names, summary: Option Summary. (line 743)
-* show-transformed-names: transform. (line 45)
-* show-transformed-names, summary: Option Summary. (line 743)
+ (line 10)
+* same-permissions, short description: Attributes. (line 109)
+* same-permissions, summary: Option Summary. (line 766)
+* same-permissions, summary <1>: Option Summary. (line 849)
+* seek, summary: Option Summary. (line 853)
+* selinux, summary: Option Summary. (line 863)
+* show-defaults: defaults. (line 6)
+* show-defaults, summary: Option Summary. (line 867)
+* show-omitted-dirs: verbose. (line 105)
+* show-omitted-dirs, summary: Option Summary. (line 880)
+* show-snapshot-field-ranges: Snapshot Files. (line 111)
+* show-snapshot-field-ranges, summary: Option Summary. (line 885)
+* show-stored-names: list. (line 68)
+* show-stored-names, summary: Option Summary. (line 891)
+* show-transformed-names: transform. (line 45)
+* show-transformed-names, summary: Option Summary. (line 891)
* skip-old-files, introduced: Dealing with Old Files.
- (line 28)
-* skip-old-files, summary: Option Summary. (line 751)
-* sort, summary: Option Summary. (line 763)
-* sparse: sparse. (line 22)
-* sparse, summary: Option Summary. (line 782)
-* sparse-version: sparse. (line 57)
-* sparse-version, summary: Option Summary. (line 787)
-* starting-file: Starting File. (line 6)
-* starting-file, summary: Option Summary. (line 792)
-* strip-components: transform. (line 25)
-* strip-components, summary: Option Summary. (line 798)
-* suffix: backup. (line 68)
-* suffix, summary: Option Summary. (line 807)
+ (line 28)
+* skip-old-files, summary: Option Summary. (line 900)
+* sort, summary: Option Summary. (line 913)
+* sparse: sparse. (line 24)
+* sparse, summary: Option Summary. (line 930)
+* sparse-version: sparse. (line 59)
+* sparse-version, summary: Option Summary. (line 936)
+* starting-file: Starting File. (line 6)
+* starting-file, summary: Option Summary. (line 942)
+* strip-components: transform. (line 25)
+* strip-components, summary: Option Summary. (line 949)
+* suffix: backup. (line 67)
+* suffix, summary: Option Summary. (line 960)
* tape-length: Multi-Volume Archives.
- (line 33)
-* tape-length, short description: Device. (line 96)
-* tape-length, summary: Option Summary. (line 811)
-* test-label: label. (line 35)
-* test-label, summary: Option Summary. (line 820)
+ (line 33)
+* tape-length, short description: Device. (line 96)
+* tape-length, summary: Option Summary. (line 965)
+* test-label: label. (line 35)
+* test-label, summary: Option Summary. (line 976)
* to-command: Writing to an External Program.
- (line 9)
-* to-command, summary: Option Summary. (line 824)
+ (line 9)
+* to-command, summary: Option Summary. (line 981)
* to-stdout: Writing to Standard Output.
- (line 14)
-* to-stdout, summary: Option Summary. (line 828)
-* totals: verbose. (line 46)
-* totals, summary: Option Summary. (line 833)
-* touch <1>: Attributes. (line 33)
+ (line 14)
+* to-stdout, summary: Option Summary. (line 986)
+* totals: verbose. (line 45)
+* totals, summary: Option Summary. (line 992)
* touch: Data Modification Times.
- (line 15)
-* touch, summary: Option Summary. (line 838)
-* transform: transform. (line 74)
-* transform, summary: Option Summary. (line 844)
-* uncompress: gzip. (line 113)
-* uncompress, summary: Option Summary. (line 153)
-* ungzip: gzip. (line 91)
-* ungzip, summary: Option Summary. (line 316)
-* unlink-first: Unlink First. (line 6)
+ (line 15)
+* touch <1>: Attributes. (line 33)
+* touch, summary: Option Summary. (line 998)
+* transform: transform. (line 74)
+* transform, summary: Option Summary. (line 1005)
+* uncompress: gzip. (line 113)
+* uncompress, summary: Option Summary. (line 164)
+* uncompress, summary <1>: Option Summary. (line 1019)
+* ungzip: gzip. (line 91)
+* ungzip, summary: Option Summary. (line 360)
+* ungzip, summary <1>: Option Summary. (line 1023)
+* unlink-first: Unlink First. (line 6)
* unlink-first, introduced: Dealing with Old Files.
- (line 52)
-* unlink-first, summary: Option Summary. (line 864)
+ (line 51)
+* unlink-first, summary: Option Summary. (line 1027)
* unquote: Selecting Archive Members.
- (line 39)
-* unquote, summary: Option Summary. (line 870)
-* update <1>: how to update. (line 6)
-* update: update. (line 6)
-* update, summary: Operation Summary. (line 50)
-* usage: help. (line 53)
-* use-compress-program: gzip. (line 177)
-* use-compress-program, summary: Option Summary. (line 874)
-* utc, summary: Option Summary. (line 879)
-* verbose: verbose. (line 18)
-* verbose, introduced: verbose tutorial. (line 6)
-* verbose, summary: Option Summary. (line 883)
-* verbose, using with --create: create verbose. (line 6)
-* verbose, using with --list: list. (line 30)
-* verify, short description: verify. (line 8)
-* verify, summary: Option Summary. (line 890)
-* verify, using with --create: verify. (line 24)
-* version: help. (line 6)
-* version, summary: Option Summary. (line 895)
+ (line 39)
+* unquote, summary: Option Summary. (line 1033)
+* update: update. (line 6)
+* update <1>: how to update. (line 6)
+* update, summary: Operation Summary. (line 60)
+* usage: help. (line 53)
+* use-compress-program: gzip. (line 172)
+* use-compress-program, summary: Option Summary. (line 1037)
+* utc, summary: Option Summary. (line 1043)
+* verbatim-files-from: files. (line 70)
+* verbatim-files-from, summary: Option Summary. (line 1048)
+* verbose: verbose. (line 18)
+* verbose, introduced: verbose tutorial. (line 6)
+* verbose, summary: Option Summary. (line 1070)
+* verbose, using with '--create': create verbose. (line 6)
+* verbose, using with '--list': list. (line 34)
+* verify, short description: verify. (line 8)
+* verify, summary: Option Summary. (line 1078)
+* verify, using with '--create': verify. (line 24)
+* version: help. (line 6)
+* version, summary: Option Summary. (line 1084)
* volno-file: Multi-Volume Archives.
- (line 79)
-* volno-file, summary: Option Summary. (line 900)
-* warning, explained: warnings. (line 12)
-* warning, summary: Option Summary. (line 905)
+ (line 74)
+* volno-file, summary: Option Summary. (line 1090)
+* warning, explained: warnings. (line 12)
+* warning, summary: Option Summary. (line 1096)
* wildcards: controlling pattern-matching.
- (line 38)
-* wildcards, summary: Option Summary. (line 910)
+ (line 38)
+* wildcards, summary: Option Summary. (line 1102)
* wildcards-match-slash: controlling pattern-matching.
+ (line 91)
+* wildcards-match-slash, summary: Option Summary. (line 1106)
+* xattrs, summary: Option Summary. (line 1109)
+* xattrs-exclude, summary: Option Summary. (line 1113)
+* xattrs-include, summary: Option Summary. (line 1117)
+* xform: transform. (line 74)
+* xform, summary: Option Summary. (line 1005)
+* xz: gzip. (line 96)
+* xz, summary: Option Summary. (line 1123)
+
+\1f
+File: tar.info, Node: Index, Prev: Index of Command Line Options, Up: Top
+
+Appendix I Index
+****************
+
+\0\b[index\0\b]
+* Menu:
+
+* '%s: Directory has been renamed from %s', warning message: warnings.
+ (line 96)
+* '%s: Directory has been renamed', warning message: warnings.
+ (line 96)
+* '%s: Directory is new', warning message: warnings. (line 98)
+* '%s: directory is on a different device: not purging', warning message: warnings.
+ (line 100)
+* '%s: skipping existing file', warning message: warnings. (line 62)
+* -after-date and -update compared: after. (line 19)
+* -newer-mtime and -update compared: after. (line 19)
+* -quite, option: Generate Mode. (line 120)
+* .bzrignore: exclude. (line 63)
+* .cvsignore: exclude. (line 50)
+* .gitignore: exclude. (line 55)
+* .hgignore: exclude. (line 70)
+* 'A lone zero block at', warning message: warnings. (line 33)
+* abbreviations for months: Calendar date items. (line 38)
+* absolute file names: absolute. (line 6)
+* absolute file names <1>: Remote Tape Server. (line 17)
+* Adding archives to an archive: concatenate. (line 6)
+* Adding files to an Archive: appending files. (line 6)
+* ADMINISTRATOR: General-Purpose Variables.
+ (line 6)
+* Age, excluding files by: after. (line 6)
+* ago in date strings: Relative items in date strings.
+ (line 23)
+* all: warnings. (line 28)
+* alone-zero-block: warnings. (line 33)
+* alternative decompression programs: gzip. (line 54)
+* am in date strings: Time of day items. (line 21)
+* Appending files to an Archive: appending files. (line 6)
+* appending files to existing archive: append. (line 6)
+* Arch, excluding files: exclude. (line 85)
+* archive: Definitions. (line 6)
+* Archive creation: file. (line 34)
+* archive member: Definitions. (line 15)
+* Archive Name: file. (line 6)
+* Archive, creation of: create. (line 6)
+* Archives, Appending files to: appending files. (line 6)
+* archives, binary equivalent: PAX keywords. (line 136)
+* Archiving Directories: create dir. (line 6)
+* archiving files: Top. (line 23)
+* ARGP_HELP_FMT, environment variable: Configuring Help Summary.
+ (line 21)
+* arguments to long options: Long Options. (line 31)
+* arguments to old options: Old Options. (line 26)
+* arguments to short options: Short Options. (line 13)
+* 'Attempting extraction of symbolic links as hard links', warning message: warnings.
+ (line 68)
+* attributes, files: Attributes. (line 6)
+* authors of 'parse_datetime': Authors of parse_datetime.
+ (line 6)
+* Avoiding recursion in directories: recurse. (line 6)
+* backup options: backup. (line 6)
+* backup suffix: backup. (line 67)
+* backups: backup. (line 41)
+* backups <1>: Backups. (line 6)
+* BACKUP_DIRS: General-Purpose Variables.
+ (line 30)
+* BACKUP_FILES: General-Purpose Variables.
+ (line 58)
+* BACKUP_HOUR: General-Purpose Variables.
+ (line 10)
+* bad-dumpdir: warnings. (line 102)
+* basic operations: Operations. (line 6)
+* Bazaar, excluding files: exclude. (line 85)
+* Bazaar, ignore files: exclude. (line 37)
+* beginning of time, for POSIX: Seconds since the Epoch.
+ (line 13)
+* 'bell', checkpoint action: checkpoints. (line 106)
+* Bellovin, Steven M.: Authors of parse_datetime.
+ (line 6)
+* Berets, Jim: Authors of parse_datetime.
+ (line 6)
+* Berry, K.: Authors of parse_datetime.
+ (line 19)
+* binary equivalent archives, creating: PAX keywords. (line 136)
+* block: Blocking. (line 6)
+* Block number where error occurred: verbose. (line 112)
+* BLOCKING: General-Purpose Variables.
+ (line 25)
+* Blocking Factor: Blocking Factor. (line 6)
+* blocking factor: Blocking Factor. (line 189)
+* Blocks per record: Blocking Factor. (line 6)
+* bug reports: Reports. (line 6)
+* Bytes per record: Blocking Factor. (line 6)
+* bzip2: gzip. (line 6)
+* cachedir: warnings. (line 40)
+* calendar date item: Calendar date items. (line 6)
+* case, ignored in dates: General date syntax. (line 60)
+* 'cat' vs 'concatenate': concatenate. (line 63)
+* Changing directory mid-stream: directory. (line 6)
+* Character class, excluding characters from: wildcards. (line 34)
+* checkpoints, defined: checkpoints. (line 6)
+* Choosing an archive file: file. (line 6)
+* combined date and time of day item: Combined date and time of day items.
+ (line 6)
+* comments, in dates: General date syntax. (line 60)
+* compress: gzip. (line 6)
+* Compressed archives: gzip. (line 6)
+* 'concatenate' vs 'cat': concatenate. (line 63)
+* Concatenating Archives: concatenate. (line 6)
+* 'contains a cache directory tag', warning message: warnings.
+ (line 40)
+* contiguous-cast: warnings. (line 66)
+* corrupted archives: Full Dumps. (line 8)
+* corrupted archives <1>: gzip. (line 140)
+* Creation of the archive: create. (line 6)
+* 'Current %s is newer or same age', warning message: warnings.
+ (line 72)
+* CVS, excluding files: exclude. (line 85)
+* CVS, ignore files: exclude. (line 37)
+* Darcs, excluding files: exclude. (line 85)
+* DAT blocking: Blocking Factor. (line 199)
+* Data Modification time, excluding files by: after. (line 6)
+* Data modification times of extracted files: Data Modification Times.
+ (line 6)
+* date and time of day format, ISO 8601: Combined date and time of day items.
+ (line 6)
+* date format, ISO 8601: Calendar date items. (line 30)
+* date input formats: Date input formats. (line 6)
+* day in date strings: Relative items in date strings.
+ (line 15)
+* day in date strings <1>: Relative items in date strings.
+ (line 29)
+* day of week item: Day of week items. (line 6)
+* decompress-program: warnings. (line 76)
+* Deleting files from an archive: delete. (line 6)
+* Deleting from tape archives: delete. (line 17)
+* dereferencing hard links: hard links. (line 6)
+* Descending directories, avoiding: recurse. (line 6)
+* Device numbers, changing: Fixing Snapshot Files.
+ (line 6)
+* Device numbers, using in incremental backups: Incremental Dumps.
+ (line 89)
+* Directories, Archiving: create dir. (line 6)
+* Directories, avoiding recursion: recurse. (line 6)
+* Directory, changing mid-stream: directory. (line 6)
+* DIRLIST: General-Purpose Variables.
+ (line 53)
+* displacement of dates: Relative items in date strings.
+ (line 6)
+* doc-opt-col: Configuring Help Summary.
+ (line 95)
+* 'door ignored', warning message: warnings. (line 45)
+* 'dot', checkpoint action: checkpoints. (line 130)
+* Double-checking a write operation: verify. (line 6)
+* dumps, full: Full Dumps. (line 8)
+* DUMP_BEGIN: User Hooks. (line 31)
+* DUMP_END: User Hooks. (line 35)
+* DUMP_REMIND_SCRIPT: General-Purpose Variables.
+ (line 112)
+* dup-args: Configuring Help Summary.
+ (line 52)
+* dup-args-note: Configuring Help Summary.
+ (line 69)
+* 'echo', checkpoint action: checkpoints. (line 25)
+* Eggert, Paul: Authors of parse_datetime.
+ (line 6)
+* End-of-archive blocks, ignoring: Ignore Zeros. (line 6)
+* End-of-archive info script: Multi-Volume Archives.
+ (line 83)
+* entry: Naming tar Archives. (line 11)
+* epoch, for POSIX: Seconds since the Epoch.
+ (line 13)
+* Error message, block number of: verbose. (line 122)
+* Exabyte blocking: Blocking Factor. (line 199)
+* exclude: exclude. (line 12)
+* exclude-caches: exclude. (line 122)
+* exclude-from: exclude. (line 25)
+* exclude-tag: exclude. (line 145)
+* Excluding characters from a character class: wildcards. (line 34)
+* Excluding file by age: after. (line 6)
+* Excluding files by file system: exclude. (line 6)
+* Excluding files by name and pattern: exclude. (line 6)
+* Exec Mode, 'genfile': Exec Mode. (line 6)
+* 'exec', checkpoint action: checkpoints. (line 151)
+* existing backup method: backup. (line 59)
+* existing-file: warnings. (line 62)
+* exit status: Synopsis. (line 67)
+* 'Extracting contiguous files as regular files', warning message: warnings.
+ (line 66)
+* extracting Nth copy of the file: append. (line 34)
+* extraction: Definitions. (line 22)
+* Extraction: extract. (line 6)
+* file archival: Top. (line 23)
+* file attributes: Attributes. (line 6)
+* 'file changed as we read it', warning message: warnings. (line 55)
+* 'file is on a different filesystem', warning message: warnings.
+ (line 43)
+* 'file is the archive; not dumped', warning message: warnings.
+ (line 51)
+* 'file is the archive; not dumped', warning message <1>: warnings.
+ (line 51)
+* 'file is unchanged; not dumped', warning message: warnings. (line 49)
+* File lists separated by NUL characters: Generate Mode. (line 33)
+* file name: Definitions. (line 15)
+* File Name arguments, alternatives: files. (line 6)
+* File name arguments, using '--list' with: list. (line 25)
+* 'file name read contains nul character', warning message: warnings.
+ (line 31)
+* file names, absolute: absolute. (line 6)
+* File names, excluding files by: exclude. (line 6)
+* File names, terminated by 'NUL': nul. (line 6)
+* File names, using hard links: hard links. (line 6)
+* File names, using symbolic links: dereference. (line 6)
+* 'File removed before we read it', warning message: warnings.
+ (line 53)
+* 'File shrank by %s bytes', warning message: warnings. (line 41)
+* File system boundaries, not crossing: one. (line 6)
+* file-changed: warnings. (line 55)
+* file-ignored: warnings. (line 45)
+* file-removed: warnings. (line 53)
+* file-shrank: warnings. (line 41)
+* file-unchanged: warnings. (line 49)
+* FILELIST: General-Purpose Variables.
+ (line 69)
+* filename-with-nuls: warnings. (line 31)
+* 'find', using with 'tar': files. (line 6)
+* 'find', using with 'tar' <1>: recurse. (line 11)
+* first in date strings: General date syntax. (line 22)
+* format 0, snapshot file: Snapshot Files. (line 24)
+* format 1, snapshot file: Snapshot Files. (line 51)
+* format 2, snapshot file: Snapshot Files. (line 73)
+* Format Options: Format Variations. (line 6)
+* Format Parameters: Format Variations. (line 6)
+* Format, old style: old. (line 6)
+* fortnight in date strings: Relative items in date strings.
+ (line 15)
+* free documentation: Free Software Needs Free Documentation.
+ (line 6)
+* full dumps: Full Dumps. (line 8)
+* future time stamps: Large or Negative Values.
+ (line 6)
+* general date syntax: General date syntax. (line 6)
+* Generate Mode, 'genfile': Generate Mode. (line 6)
+* genfile: Genfile. (line 6)
+* 'genfile', create file: Generate Mode. (line 6)
+* 'genfile', creating sparse files: Generate Mode. (line 55)
+* 'genfile', generate mode: Generate Mode. (line 6)
+* 'genfile', reading a list of file names: Generate Mode. (line 22)
+* 'genfile', seeking to a given offset: Generate Mode. (line 18)
+* Getting program version number: help. (line 6)
+* git, excluding files: exclude. (line 85)
+* Git, ignore files: exclude. (line 37)
+* GNU archive format: gnu. (line 6)
+* GNU.sparse.major, extended header variable: PAX 1. (line 14)
+* GNU.sparse.map, extended header variable: PAX 0. (line 59)
+* GNU.sparse.minor, extended header variable: PAX 1. (line 17)
+* GNU.sparse.name, extended header variable: PAX 0. (line 67)
+* GNU.sparse.name, extended header variable, in v.1.0: PAX 1. (line 24)
+* GNU.sparse.numblocks, extended header variable: PAX 0. (line 14)
+* GNU.sparse.numbytes, extended header variable: PAX 0. (line 20)
+* GNU.sparse.offset, extended header variable: PAX 0. (line 17)
+* GNU.sparse.realsize, extended header variable: PAX 1. (line 24)
+* GNU.sparse.size, extended header variable: PAX 0. (line 10)
+* gnupg, using with tar: gzip. (line 196)
+* gpg, using with tar: gzip. (line 196)
+* gzip: gzip. (line 6)
+* hard links, dereferencing: hard links. (line 6)
+* header-col: Configuring Help Summary.
+ (line 141)
+* hole detection: sparse. (line 66)
+* hook: User Hooks. (line 12)
+* hour in date strings: Relative items in date strings.
+ (line 15)
+* ignore-archive: warnings. (line 51)
+* ignore-archive <1>: warnings. (line 51)
+* ignore-newer: warnings. (line 72)
+* Ignoring end-of-archive blocks: Ignore Zeros. (line 6)
+* 'Ignoring unknown extended header keyword '%s'', warning message: warnings.
+ (line 74)
+* 'implausibly old time stamp %s', warning message: warnings. (line 63)
+* Info script: Multi-Volume Archives.
+ (line 83)
+* Interactive operation: interactive. (line 6)
+* ISO 8601 date and time of day format: Combined date and time of day items.
+ (line 6)
+* ISO 8601 date format: Calendar date items. (line 30)
+* items in date strings: General date syntax. (line 6)
+* Labeling an archive: label. (line 6)
+* labeling archives: Tape Files. (line 6)
+* Labeling multi-volume archives: label. (line 6)
+* Labels on the archive media: label. (line 6)
+* language, in dates: General date syntax. (line 36)
+* language, in dates <1>: General date syntax. (line 40)
+* Large lists of file names on small machines: Same Order. (line 6)
+* large values: Large or Negative Values.
+ (line 6)
+* last DAY: Day of week items. (line 15)
+* last in date strings: General date syntax. (line 22)
+* Laszlo Ersek: lbzip2. (line 6)
+* lbzip2: lbzip2. (line 6)
+* leap seconds: General date syntax. (line 65)
+* leap seconds <1>: Time of day items. (line 14)
+* leap seconds <2>: Seconds since the Epoch.
+ (line 26)
+* Listing all 'tar' options: help. (line 26)
+* listing member and file names: list. (line 45)
+* Listing volume label: label. (line 27)
+* Lists of file names: files. (line 6)
+* Local and remote archives: file. (line 70)
+* long options: Long Options. (line 6)
+* long options with mandatory arguments: Long Options. (line 31)
+* long options with optional arguments: Long Options. (line 39)
+* long-opt-col: Configuring Help Summary.
+ (line 87)
+* lzip: gzip. (line 6)
+* lzma: gzip. (line 6)
+* lzop: gzip. (line 6)
+* MacKenzie, David: Authors of parse_datetime.
+ (line 6)
+* 'Malformed dumpdir: 'X' never used', warning message: warnings.
+ (line 102)
+* member: Definitions. (line 15)
+* member name: Definitions. (line 15)
+* members, multiple: multiple. (line 6)
+* Members, replacing with other members: append. (line 47)
+* Mercurial, excluding files: exclude. (line 85)
+* Mercurial, ignore files: exclude. (line 37)
+* Meyering, Jim: Authors of parse_datetime.
+ (line 6)
+* Middle of the archive, starting in the: Starting File. (line 11)
+* midnight in date strings: Time of day items. (line 21)
+* minute in date strings: Relative items in date strings.
+ (line 15)
+* minutes, time zone correction by: Time of day items. (line 29)
+* Modes of extracted files: Setting Access Permissions.
+ (line 6)
+* Modification time, excluding files by: after. (line 6)
+* Modification times of extracted files: Data Modification Times.
+ (line 6)
+* month in date strings: Relative items in date strings.
+ (line 15)
+* month names in date strings: Calendar date items. (line 38)
+* months, written-out: General date syntax. (line 32)
+* MT: General-Purpose Variables.
+ (line 74)
+* MT_BEGIN: Magnetic Tape Control.
+ (line 10)
+* MT_OFFLINE: Magnetic Tape Control.
+ (line 30)
+* MT_REWIND: Magnetic Tape Control.
+ (line 20)
+* MT_STATUS: Magnetic Tape Control.
+ (line 40)
+* Multi-volume archives: Multi-Volume Archives.
+ (line 6)
+* Multi-volume archives in PAX format, extracting using non-GNU tars: Split Recovery.
+ (line 17)
+* Multi-volume archives, extracting using non-GNU tars: Split Recovery.
+ (line 6)
+* multiple members: multiple. (line 6)
+* Naming an archive: file. (line 6)
+* negative time stamps: Large or Negative Values.
+ (line 6)
+* new-directory: warnings. (line 98)
+* next DAY: Day of week items. (line 15)
+* next in date strings: General date syntax. (line 22)
+* none: warnings. (line 29)
+* noon in date strings: Time of day items. (line 21)
+* now in date strings: Relative items in date strings.
+ (line 33)
+* ntape device: Many. (line 6)
+* 'NUL'-terminated file names: nul. (line 6)
+* Number of blocks per record: Blocking Factor. (line 6)
+* Number of bytes per record: Blocking Factor. (line 6)
+* numbered backup method: backup. (line 55)
+* numbers, written-out: General date syntax. (line 22)
+* Obtaining help: help. (line 26)
+* Obtaining total status information: verbose. (line 45)
+* Old GNU archive format: gnu. (line 6)
+* Old GNU sparse format: Old GNU Format. (line 6)
+* old option style: Old Options. (line 6)
+* old options with mandatory arguments: Old Options. (line 26)
+* Old style archives: old. (line 6)
+* Old style format: old. (line 6)
+* opt-doc-col: Configuring Help Summary.
+ (line 127)
+* option syntax, traditional: Old Options. (line 6)
+* optional arguments to long options: Long Options. (line 39)
+* optional arguments to short options: Short Options. (line 22)
+* options for use with '--extract': extract options. (line 6)
+* Options when reading archives: Reading. (line 6)
+* Options, archive format specifying: Format Variations. (line 6)
+* Options, format specifying: Format Variations. (line 6)
+* options, GNU style: Long Options. (line 6)
+* options, long style: Long Options. (line 6)
+* options, mixing different styles: Mixing. (line 6)
+* options, mnemonic names: Long Options. (line 6)
+* options, old style: Old Options. (line 6)
+* options, short style: Short Options. (line 6)
+* options, traditional: Short Options. (line 6)
+* ordinal numbers: General date syntax. (line 22)
+* Overwriting old files, prevention: Dealing with Old Files.
+ (line 16)
+* parse_datetime: Date input formats. (line 6)
+* pattern, 'genfile': Generate Mode. (line 39)
+* PAX archive format: posix. (line 6)
+* Permissions of extracted files: Setting Access Permissions.
+ (line 6)
+* Pinard, F.: Authors of parse_datetime.
+ (line 19)
+* pm in date strings: Time of day items. (line 21)
+* POSIX archive format: posix. (line 6)
+* Progress information: verbose. (line 82)
+* Protecting old files: Dealing with Old Files.
+ (line 36)
+* pure numbers in date strings: Pure numbers in date strings.
+ (line 6)
+* RCS, excluding files: exclude. (line 85)
+* Reading file names from a file: files. (line 6)
+* Reading incomplete records: Reading. (line 6)
+* record: Blocking. (line 6)
+* Record Size: Blocking Factor. (line 6)
+* 'Record size = %lu blocks', warning message: warnings. (line 89)
+* record-size: warnings. (line 89)
+* Records, incomplete: Reading. (line 6)
+* Recursion in directories, avoiding: recurse. (line 6)
+* relative items in date strings: Relative items in date strings.
+ (line 6)
+* Remote devices: file. (line 60)
+* remote tape drive: Remote Tape Server. (line 6)
+* Removing files from an archive: delete. (line 6)
+* rename-directory: warnings. (line 96)
+* Replacing members with other members: append. (line 47)
+* reporting bugs: Reports. (line 6)
+* RESTORE_BEGIN: User Hooks. (line 38)
+* RESTORE_END: User Hooks. (line 41)
+* Resurrecting files from an archive: extract. (line 6)
+* Retrieving files from an archive: extract. (line 6)
+* return status: Synopsis. (line 67)
+* rmargin: Configuring Help Summary.
+ (line 159)
+* rmt: Remote Tape Server. (line 6)
+* RSH: General-Purpose Variables.
+ (line 78)
+* RSH_COMMAND: General-Purpose Variables.
+ (line 83)
+* Running out of space: Scarce. (line 8)
+* Salz, Rich: Authors of parse_datetime.
+ (line 6)
+* SCCS, excluding files: exclude. (line 85)
+* short options: Short Options. (line 6)
+* short options with mandatory arguments: Short Options. (line 13)
+* short options with optional arguments: Short Options. (line 22)
+* short-opt-col: Configuring Help Summary.
+ (line 79)
+* simple backup method: backup. (line 64)
+* SIMPLE_BACKUP_SUFFIX: backup. (line 67)
+* 'sleep', checkpoint action: checkpoints. (line 145)
+* SLEEP_MESSAGE: General-Purpose Variables.
+ (line 121)
+* SLEEP_TIME: General-Purpose Variables.
+ (line 106)
+* Small memory: Scarce. (line 8)
+* snapshot file field ranges: Snapshot Files. (line 111)
+* snapshot file, format 0: Snapshot Files. (line 24)
+* snapshot file, format 1: Snapshot Files. (line 51)
+* snapshot file, format 2: Snapshot Files. (line 73)
+* snapshot files, editing: Fixing Snapshot Files.
+ (line 6)
+* snapshot files, fixing device numbers: Fixing Snapshot Files.
+ (line 6)
+* 'socket ignored', warning message: warnings. (line 45)
+* Sparse Files: sparse. (line 6)
+* sparse files v.0.0, extracting with non-GNU tars: Sparse Recovery.
+ (line 92)
+* sparse files v.0.1, extracting with non-GNU tars: Sparse Recovery.
(line 92)
-* wildcards-match-slash, summary: Option Summary. (line 914)
-* xform: transform. (line 74)
-* xform, summary: Option Summary. (line 844)
-* xz: gzip. (line 96)
-* xz, summary: Option Summary. (line 917)
+* sparse files v.1.0, extracting with non-GNU tars: Sparse Recovery.
+ (line 17)
+* Sparse files, creating using 'genfile': Generate Mode. (line 55)
+* sparse files, extracting with non-GNU tars: Sparse Recovery.
+ (line 6)
+* sparse formats: Sparse Formats. (line 6)
+* sparse formats, defined: sparse. (line 52)
+* sparse formats, Old GNU: Old GNU Format. (line 6)
+* sparse formats, v.0.0: PAX 0. (line 6)
+* sparse formats, v.0.1: PAX 0. (line 51)
+* sparse formats, v.1.0: PAX 1. (line 6)
+* sparse versions: Sparse Formats. (line 6)
+* Specifying archive members: Selecting Archive Members.
+ (line 6)
+* Specifying files to act on: Selecting Archive Members.
+ (line 6)
+* Standard input and output: file. (line 39)
+* Standard output, writing extracted files to: Writing to Standard Output.
+ (line 6)
+* Storing archives in compressed format: gzip. (line 6)
+* SVN, excluding files: exclude. (line 85)
+* Symbolic link as file name: dereference. (line 6)
+* symlink-cast: warnings. (line 68)
+* TAPE: file tutorial. (line 14)
+* tape blocking: Blocking Factor. (line 189)
+* tape marks: Many. (line 43)
+* tape positioning: Many. (line 26)
+* Tapes, using '--delete' and: delete. (line 17)
+* TAPE_FILE: General-Purpose Variables.
+ (line 18)
+* tar: What tar Does. (line 6)
+* TAR: General-Purpose Variables.
+ (line 126)
+* tar archive: Definitions. (line 6)
+* Tar archive formats: Formats. (line 6)
+* tar entry: Naming tar Archives. (line 11)
+* tar file: Naming tar Archives. (line 11)
+* tar to a remote device: file. (line 60)
+* tar to standard input and output: file. (line 39)
+* tar-snapshot-edit: Fixing Snapshot Files.
+ (line 17)
+* tarcat: Tarcat. (line 6)
+* TAR_ARCHIVE, checkpoint script environment: checkpoints. (line 167)
+* TAR_ARCHIVE, info script environment variable: Multi-Volume Archives.
+ (line 105)
+* TAR_ARCHIVE, to-command environment: Writing to an External Program.
+ (line 79)
+* TAR_ATIME, to-command environment: Writing to an External Program.
+ (line 52)
+* TAR_BLOCKING_FACTOR, checkpoint script environment: checkpoints.
+ (line 170)
+* TAR_BLOCKING_FACTOR, info script environment variable: Multi-Volume Archives.
+ (line 108)
+* TAR_BLOCKING_FACTOR, to-command environment: Writing to an External Program.
+ (line 82)
+* TAR_CHECKPOINT, checkpoint script environment: checkpoints. (line 173)
+* TAR_CTIME, to-command environment: Writing to an External Program.
+ (line 61)
+* TAR_FD, info script environment variable: Multi-Volume Archives.
+ (line 122)
+* TAR_FILENAME, to-command environment: Writing to an External Program.
+ (line 40)
+* TAR_FILETYPE, to-command environment: Writing to an External Program.
+ (line 24)
+* TAR_FORMAT, checkpoint script environment: checkpoints. (line 180)
+* TAR_FORMAT, info script environment variable: Multi-Volume Archives.
+ (line 118)
+* TAR_FORMAT, to-command environment: Writing to an External Program.
+ (line 88)
+* TAR_GID, to-command environment: Writing to an External Program.
+ (line 70)
+* TAR_GNAME, to-command environment: Writing to an External Program.
+ (line 49)
+* TAR_MODE, to-command environment: Writing to an External Program.
+ (line 37)
+* TAR_MTIME, to-command environment: Writing to an External Program.
+ (line 58)
+* TAR_OPTIONS, environment variable: using tar options. (line 30)
+* TAR_REALNAME, to-command environment: Writing to an External Program.
+ (line 43)
+* TAR_SIZE, to-command environment: Writing to an External Program.
+ (line 64)
+* TAR_SUBCOMMAND, checkpoint script environment: checkpoints. (line 176)
+* TAR_SUBCOMMAND, info script environment variable: Multi-Volume Archives.
+ (line 114)
+* TAR_UID, to-command environment: Writing to an External Program.
+ (line 67)
+* TAR_UNAME, to-command environment: Writing to an External Program.
+ (line 46)
+* TAR_VERSION, checkpoint script environment: checkpoints. (line 164)
+* TAR_VERSION, info script environment variable: Multi-Volume Archives.
+ (line 102)
+* TAR_VERSION, to-command environment: Writing to an External Program.
+ (line 76)
+* TAR_VOLUME, info script environment variable: Multi-Volume Archives.
+ (line 111)
+* TAR_VOLUME, to-command environment: Writing to an External Program.
+ (line 85)
+* this in date strings: Relative items in date strings.
+ (line 33)
+* time of day item: Time of day items. (line 6)
+* 'time stamp %s is %s s in the future', warning message: warnings.
+ (line 63)
+* time zone correction: Time of day items. (line 29)
+* time zone item: General date syntax. (line 40)
+* time zone item <1>: Time zone items. (line 6)
+* timestamp: warnings. (line 63)
+* today in date strings: Relative items in date strings.
+ (line 33)
+* tomorrow in date strings: Relative items in date strings.
+ (line 29)
+* 'totals', checkpoint action: checkpoints. (line 140)
+* 'ttyout', checkpoint action: checkpoints. (line 111)
+* TZ: Specifying time zone rules.
+ (line 6)
+* Ultrix 3.1 and write failure: Remote Tape Server. (line 40)
+* 'Unknown file type '%c', extracted as normal file', warning message: warnings.
+ (line 70)
+* 'Unknown file type; file ignored', warning message: warnings.
+ (line 45)
+* unknown-cast: warnings. (line 70)
+* unknown-keyword: warnings. (line 74)
+* unpacking: Definitions. (line 22)
+* Updating an archive: update. (line 6)
+* usage-indent: Configuring Help Summary.
+ (line 155)
+* Using encrypted archives: gzip. (line 196)
+* ustar archive format: ustar. (line 6)
+* uuencode: Applications. (line 8)
+* v7 archive format: old. (line 6)
+* VCS, excluding files: exclude. (line 85)
+* VCS, excluding patterns from ignore files: exclude. (line 37)
+* VCS, ignore files: exclude. (line 37)
+* Verbose operation: verbose. (line 18)
+* Verifying a write operation: verify. (line 6)
+* Verifying the currency of an archive: compare. (line 6)
+* version control system, excluding files: exclude. (line 85)
+* Version of the 'tar' program: help. (line 6)
+* version-control Emacs variable: backup. (line 49)
+* VERSION_CONTROL: backup. (line 41)
+* volno file: Multi-Volume Archives.
+ (line 74)
+* VOLNO_FILE: General-Purpose Variables.
+ (line 89)
+* Volume label, listing: label. (line 27)
+* Volume number file: Multi-Volume Archives.
+ (line 74)
+* week in date strings: Relative items in date strings.
+ (line 15)
+* Where is the archive?: file. (line 6)
+* Working directory, specifying: directory. (line 6)
+* Writing extracted files to standard output: Writing to Standard Output.
+ (line 6)
+* Writing new archives: file. (line 34)
+* xdev: warnings. (line 43)
+* xdev <1>: warnings. (line 100)
+* XLIST: General-Purpose Variables.
+ (line 95)
+* xsparse: Sparse Recovery. (line 13)
+* year in date strings: Relative items in date strings.
+ (line 15)
+* yesterday in date strings: Relative items in date strings.
+ (line 29)
projects / debian / tar / blobdiff