-GZIP(1) GZIP(1)
+GZIP(1) General Commands Manual GZIP(1)
1mNAME0m
gzip, gunzip, zcat - compress or expand files
1mSYNOPSIS0m
- 1mgzip 22m[ 1m-acdfhlLnNrtvV19 22m] [1m-S suffix22m] [ 4mname24m 4m...24m ]
- 1mgunzip 22m[ 1m-acfhlLnNrtvV 22m] [1m-S suffix22m] [ 4mname24m 4m...24m ]
+ 1mgzip 22m[ 1m-acdfhklLnNrtvV19 22m] [1m-S suffix22m] [ 4mname24m 4m...24m ]
+ 1mgunzip 22m[ 1m-acfhklLnNrtvV 22m] [1m-S suffix22m] [ 4mname24m 4m...24m ]
1mzcat 22m[ 1m-fhLV 22m] [ 4mname24m 4m...24m ]
1mDESCRIPTION0m
4mGzip24m reduces the size of the named files using Lempel-Ziv coding
(LZ77). Whenever possible, each file is replaced by one with the
- extension 1m.gz, 22mwhile keeping the same ownership modes, access and modi-
- fication times. (The default extension is 1m-gz 22mfor VMS, 1mz 22mfor MSDOS,
- OS/2 FAT, Windows NT FAT and Atari.) If no files are specified, or if
- a file name is "-", the standard input is compressed to the standard
- output. 4mGzip24m will only attempt to compress regular files. In particu-
- lar, it will ignore symbolic links.
+ extension 1m.gz22m, while keeping the same ownership modes, access and modi-
+ fication times. (The default extension is 1mz 22mfor MSDOS, OS/2 FAT, Win-
+ dows NT FAT and Atari.) If no files are specified, or if a file name
+ is "-", the standard input is compressed to the standard output. 4mGzip0m
+ will only attempt to compress regular files. In particular, it will
+ ignore symbolic links.
If the compressed file name is too long for its file system, 4mgzip24m trun-
cates it. 4mGzip24m attempts to truncate only the parts of the file name
By default, 4mgzip24m keeps the original file name and timestamp in the com-
pressed file. These are used when decompressing the file with the 1m-N0m
option. This is useful when the compressed file name was truncated or
- when the time stamp was not preserved after a file transfer.
+ when the timestamp was not preserved after a file transfer.
Compressed files can be restored to their original form using 4mgzip24m 4m-d0m
- or 4mgunzip24m or 4mzcat.24m If the original name saved in the compressed file
+ or 4mgunzip24m or 4mzcat24m. If the original name saved in the compressed file
is not suitable for its file system, a new name is constructed from the
original one to make it legal.
compressing, 4mgzip24m uses the 1m.tgz 22mextension if necessary instead of trun-
cating a file with a 1m.tar 22mextension.
- 4mgunzip24m can currently decompress files created by 4mgzip,24m 4mzip,24m 4mcompress,0m
- 4mcompress24m 4m-H24m or 4mpack.24m The detection of the input format is automatic.
- When using the first two formats, 4mgunzip24m checks a 32 bit CRC. For 4mpack,0m
- 4mgunzip24m checks the uncompressed length. The standard 4mcompress24m format was
- not designed to allow consistency checks. However 4mgunzip24m is sometimes
- able to detect a bad .Z file. If you get an error when uncompressing a
- .Z file, do not assume that the .Z file is correct simply because the
- standard 4muncompress24m does not complain. This generally means that the
- standard 4muncompress24m does not check its input, and happily generates
- garbage output. The SCO compress -H format (lzh compression method)
- does not include a CRC but also allows some consistency checks.
+ 4mgunzip24m can currently decompress files created by 4mgzip24m, 4mzip24m, 4mcompress24m,
+ 4mcompress24m 4m-H24m or 4mpack24m. The detection of the input format is automatic.
+ When using the first two formats, 4mgunzip24m checks a 32 bit CRC. For 4mpack0m
+ and 4mgunzip24m checks the uncompressed length. The standard 4mcompress24m format
+ was not designed to allow consistency checks. However 4mgunzip24m is some-
+ times able to detect a bad .Z file. If you get an error when uncom-
+ pressing a .Z file, do not assume that the .Z file is correct simply
+ because the standard 4muncompress24m does not complain. This generally means
+ that the standard 4muncompress24m does not check its input, and happily gen-
+ erates garbage output. The SCO compress -H format (lzh compression
+ method) does not include a CRC but also allows some consistency checks.
Files created by 4mzip24m can be uncompressed by gzip only if they have a
single member compressed with the 'deflation' method. This feature is
only intended to help conversion of tar.zip files to the tar.gz format.
To extract a 4mzip24m file with a single member, use a command like 4mgunzip0m
4m<foo.zip24m or 4mgunzip24m 4m-S24m 4m.zip24m 4mfoo.zip24m. To extract zip files with several
- members, use 4munzip24m instead of 4mgunzip.0m
+ members, use 4munzip24m instead of 4mgunzip24m.
- 4mzcat24m is identical to 4mgunzip24m 1m-c. 22m(On some systems, 4mzcat24m may be
- installed as 4mgzcat24m to preserve the original link to 4mcompress.)24m 4mzcat0m
+ 4mzcat24m is identical to 4mgunzip24m 1m-c22m. (On some systems, 4mzcat24m may be
+ installed as 4mgzcat24m to preserve the original link to 4mcompress24m.) 4mzcat0m
uncompresses either a list of files on the command line or its standard
input and writes the uncompressed data on standard output. 4mzcat24m will
uncompress files that have the correct magic number whether they have a
of used disk blocks almost never increases. 4mgzip24m preserves the mode,
ownership and timestamps of files when compressing or decompressing.
- The 4mgzip24m file format is specified in P. Deutsch, GZIP file format spec-
- ification version 4.3, <ftp://ftp.isi.edu/in-notes/rfc1952.txt>, Inter-
- net RFC 1952 (May 1996). The 4mzip24m deflation format is specified in P.
- Deutsch, DEFLATE Compressed Data Format Specification version 1.3,
- <ftp://ftp.isi.edu/in-notes/rfc1951.txt>, Internet RFC 1951 (May 1996).
-
1mOPTIONS0m
1m-a --ascii0m
Ascii text mode: convert end-of-lines using local conventions.
Force compression or decompression even if the file has multiple
links or the corresponding file already exists, or if the com-
pressed data is read from or written to a terminal. If the input
- data is not in a format recognized by 4mgzip,24m and if the option
+ data is not in a format recognized by 4mgzip24m, and if the option
--stdout is also given, copy the input data without change to
- the standard output: let 4mzcat24m behave as 4mcat.24m If 1m-f 22mis not
+ the standard output: let 4mzcat24m behave as 4mcat24m. If 1m-f 22mis not
given, and when not running in the background, 4mgzip24m prompts to
verify whether an existing file should be overwritten.
1m-h --help0m
Display a help screen and quit.
+ 1m-k --keep0m
+ Keep (don't delete) input files during compression or decompres-
+ sion.
+
1m-l --list0m
For each compressed file, list the following fields:
ratio: compression ratio (0.0% if unknown)
uncompressed_name: name of the uncompressed file
- The uncompressed size is given as -1 for files not in gzip for-
- mat, such as compressed .Z files. To get the uncompressed size
+ The uncompressed size is given as -1 for files not in gzip for-
+ mat, such as compressed .Z files. To get the uncompressed size
for such a file, you can use:
zcat file.Z | wc -c
- In combination with the --verbose option, the following fields
+ In combination with the --verbose option, the following fields
are also displayed:
method: compression method
crc: the 32-bit CRC of the uncompressed data
- date & time: time stamp for the uncompressed file
+ date & time: timestamp for the uncompressed file
- The compression methods currently supported are deflate, com-
- press, lzh (SCO compress -H) and pack. The crc is given as
+ The compression methods currently supported are deflate, com-
+ press, lzh (SCO compress -H) and pack. The crc is given as
ffffffff for a file not in gzip format.
- With --name, the uncompressed name, date and time are those
+ With --name, the uncompressed name, date and time are those
stored within the compress file if present.
- With --verbose, the size totals and compression ratio for all
- files is also displayed, unless some sizes are unknown. With
+ With --verbose, the size totals and compression ratio for all
+ files is also displayed, unless some sizes are unknown. With
--quiet, the title and totals lines are not displayed.
1m-L --license0m
Display the 4mgzip24m license and quit.
1m-n --no-name0m
- When compressing, do not save the original file name and time
+ When compressing, do not save the original file name and time-
stamp by default. (The original name is always saved if the name
- had to be truncated.) When decompressing, do not restore the
- original file name if present (remove only the 4mgzip24m suffix from
- the compressed file name) and do not restore the original time
+ had to be truncated.) When decompressing, do not restore the
+ original file name if present (remove only the 4mgzip24m suffix from
+ the compressed file name) and do not restore the original time-
stamp if present (copy it from the compressed file). This option
is the default when decompressing.
1m-N --name0m
- When compressing, always save the original file name and time
- stamp; this is the default. When decompressing, restore the
- original file name and time stamp if present. This option is
- useful on systems which have a limit on file name length or when
- the time stamp has been lost after a file transfer.
+ When compressing, always save the original file name and time-
+ stamp; this is the default. When decompressing, restore the
+ original file name and timestamp if present. This option is use-
+ ful on systems which have a limit on file name length or when
+ the timestamp has been lost after a file transfer.
1m-q --quiet0m
Suppress all warnings.
1m-r --recursive0m
- Travel the directory structure recursively. If any of the file
- names specified on the command line are directories, 4mgzip24m will
- descend into the directory and compress all the files it finds
+ Travel the directory structure recursively. If any of the file
+ names specified on the command line are directories, 4mgzip24m will
+ descend into the directory and compress all the files it finds
there (or decompress them in the case of 4mgunzip24m ).
1m-S .suf --suffix .suf0m
When compressing, use suffix .suf instead of .gz. Any non-empty
- suffix can be given, but suffixes other than .z and .gz should
- be avoided to avoid confusion when files are transferred to
+ suffix can be given, but suffixes other than .z and .gz should
+ be avoided to avoid confusion when files are transferred to
other systems.
- When decompressing, add .suf to the beginning of the list of
+ When decompressing, add .suf to the beginning of the list of
suffixes to try, when deriving an output file name from an input
file name.
- 4mpack24m(1)4m.0m
+ 1m--synchronous0m
+ Use synchronous output. With this option, 4mgzip24m is less likely
+ to lose data during a system crash, but it can be considerably
+ slower.
1m-t --test0m
Test. Check the compressed file integrity.
quit.
1m-# --fast --best0m
- Regulate the speed of compression using the specified digit 4m#24m,
- where 1m-1 22mor 1m--fast 22mindicates the fastest compression method
- (less compression) and 1m-9 22mor 1m--best 22mindicates the slowest com-
- pression method (best compression). The default compression
+ Regulate the speed of compression using the specified digit 4m#24m,
+ where 1m-1 22mor 1m--fast 22mindicates the fastest compression method
+ (less compression) and 1m-9 22mor 1m--best 22mindicates the slowest com-
+ pression method (best compression). The default compression
level is 1m-6 22m(that is, biased towards high compression at expense
of speed).
+ 1m--rsyncable0m
+ When you synchronize a compressed file between two computers,
+ this option allows rsync to transfer only files that were
+ changed in the archive instead of the entire archive. Normally,
+ after a change is made to any file in the archive, the compres-
+ sion algorithm can generate a new version of the archive that
+ does not match the previous version of the archive. In this
+ case, rsync transfers the entire new version of the archive to
+ the remote computer. With this option, rsync can transfer only
+ the changed files as well as a small amount of metadata that is
+ required to update the archive structure in the area that was
+ changed.
+
1mADVANCED USAGE0m
- Multiple compressed files can be concatenated. In this case, 4mgunzip0m
+ Multiple compressed files can be concatenated. In this case, 4mgunzip0m
will extract all members at once. For example:
gzip -c file1 > foo.gz
cat file1 file2
- In case of damage to one member of a .gz file, other members can still
- be recovered (if the damaged member is removed). However, you can get
+ In case of damage to one member of a .gz file, other members can still
+ be recovered (if the damaged member is removed). However, you can get
better compression by compressing all members at once:
cat file1 file2 | gzip > foo.gz
gzip -cd old.gz | gzip > new.gz
If a compressed file consists of several members, the uncompressed size
- and CRC reported by the --list option applies to the last member only.
+ and CRC reported by the --list option applies to the last member only.
If you need the uncompressed size for all members, you can use:
gzip -cd file.gz | wc -c
- If you wish to create a single archive file with multiple members so
+ If you wish to create a single archive file with multiple members so
that members can later be extracted independently, use an archiver such
- as tar or zip. GNU tar supports the -z option to invoke gzip transpar-
+ as tar or zip. GNU tar supports the -z option to invoke gzip transpar-
ently. gzip is designed as a complement to tar, not as a replacement.
1mENVIRONMENT0m
- The environment variable 1mGZIP 22mcan hold a set of default options for
- 4mgzip.24m These options are interpreted first and can be overwritten by
- explicit command line parameters. For example:
- for sh: GZIP="-8v --name"; export GZIP
- for csh: setenv GZIP "-8v --name"
- for MSDOS: set GZIP=-8v --name
-
- On Vax/VMS, the name of the environment variable is GZIP_OPT, to avoid
- a conflict with the symbol set for invocation of the program.
+ The obsolescent environment variable 1mGZIP 22mcan hold a set of default
+ options for 4mgzip24m. These options are interpreted first and can be over-
+ written by explicit command line parameters. As this can cause prob-
+ lems when using scripts, this feature is supported only for options
+ that are reasonably likely to not cause too much harm, and 4mgzip24m warns
+ if it is used. This feature will be removed in a future release of
+ 4mgzip24m.
+
+ You can use an alias or script instead. For example, if 4mgzip24m is in the
+ directory 1m/usr/bin 22myou can prepend 1m$HOME/bin 22mto your 1mPATH 22mand create an
+ executable script 1m$HOME/bin/gzip 22mcontaining the following:
+
+ #! /bin/sh
+ export PATH=/usr/bin
+ exec gzip -9 "$@"
1mSEE ALSO0m
znew(1), zcmp(1), zmore(1), zforce(1), gzexe(1), zip(1), unzip(1), com-
- press(1), pack(1), compact(1)
+ press(1)
The 4mgzip24m file format is specified in P. Deutsch, GZIP file format spec-
- ification version 4.3, 1m<ftp://ftp.isi.edu/in-notes/rfc1952.txt>22m, Inter-
- net RFC 1952 (May 1996). The 4mzip24m deflation format is specified in P.
+ ification version 4.3, 1m<https://www.ietf.org/rfc/rfc1952.txt>22m, Internet
+ RFC 1952 (May 1996). The 4mzip24m deflation format is specified in P.
Deutsch, DEFLATE Compressed Data Format Specification version 1.3,
- 1m<ftp://ftp.isi.edu/in-notes/rfc1951.txt>22m, Internet RFC 1951 (May 1996).
+ 1m<https://www.ietf.org/rfc/rfc1951.txt>22m, Internet RFC 1951 (May 1996).
1mDIAGNOSTICS0m
Exit status is normally 0; if an error occurs, exit status is 1. If a
warning occurs, exit status is 2.
- Usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...]
+ Usage: gzip [-cdfhklLnNrtvV19] [-S suffix] [file ...]
Invalid options were specified on the command line.
4mfile24m: not in gzip format
press the file with gzip, which compresses better and uses less
memory.
- 4mfile24m: already has .gz suffix -- no change
+ 4mfile24m: already has .gz suffix -- unchanged
The file is assumed to be already compressed. Rename the file
and try again.
pad the output with zeroes up to a block boundary. When the data is
read and the whole block is passed to 4mgunzip24m for decompression, 4mgunzip0m
detects that there is extra trailing garbage after the compressed data
- and emits a warning by default. You have to use the --quiet option to
- suppress the warning. This option can be set in the 1mGZIP 22menvironment
- variable as in:
- for sh: GZIP="-q" tar -xfz --block-compress /dev/rst0
- for csh: (setenv GZIP -q; tar -xfz --block-compr /dev/rst0
-
- In the above example, gzip is invoked implicitly by the -z option of
- GNU tar. Make sure that the same block size (-b option of tar) is used
- for reading and writing compressed data on tapes. (This example
- assumes you are using the GNU version of tar.)
+ and emits a warning by default. You can use the --quiet option to sup-
+ press the warning.
1mBUGS0m
The gzip format represents the input size modulo 2^32, so the --list
In some rare cases, the --best option gives worse compression than the
default compression level (-6). On some highly redundant files, 4mcom-0m
- 4mpress24m compresses better than 4mgzip.0m
+ 4mpress24m compresses better than 4mgzip24m.
1mCOPYRIGHT NOTICE0m
- Copyright (C) 1998, 1999, 2001, 2002 Free Software Foundation, Inc.
+ Copyright (C) 1998-1999, 2001-2002, 2012, 2015-2018 Free Software Foun-
+ dation, Inc.
Copyright (C) 1992, 1993 Jean-loup Gailly
- Permission is granted to make and distribute verbatim copies of this
- manual provided the copyright notice and this permission notice are
+ Permission is granted to make and distribute verbatim copies of this
+ manual provided the copyright notice and this permission notice are
preserved on all copies.
- Permission is granted to copy and distribute modified versions of this
- manual under the conditions for verbatim copying, provided that the
- entire resulting derived work is distributed under the terms of a per-
+ Permission is granted to copy and distribute modified versions of this
+ manual under the conditions for verbatim copying, provided that the
+ entire resulting derived work is distributed under the terms of a per-
mission notice identical to this one.
- Permission is granted to copy and distribute translations of this man-
+ Permission is granted to copy and distribute translations of this man-
ual into another language, under the above conditions for modified ver-
- sions, except that this permission notice may be stated in a transla-
+ sions, except that this permission notice may be stated in a transla-
tion approved by the Foundation.
local GZIP(1)
projects / debian / gzip / blobdiff