X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=gzip.doc;h=0286afa83f853109f664be687dd53e3615934e9c;hb=92249085071a973e2c0621b0415b93d2e48bb00d;hp=da8dad1ad6b06b4beeeee0a30b2c559f69077ebd;hpb=dc84183747ce1703eb99685b5dbde1f65a143c06;p=debian%2Fgzip diff --git a/gzip.doc b/gzip.doc index da8dad1..0286afa 100644 --- a/gzip.doc +++ b/gzip.doc @@ -1,22 +1,22 @@ -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 @@ -29,10 +29,10 @@ GZIP(1) GZIP(1) 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. @@ -44,27 +44,27 @@ GZIP(1) GZIP(1) 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, Inter- - net RFC 1952 (May 1996). The 4mzip24m deflation format is specified in P. - Deutsch, DEFLATE Compressed Data Format Specification version 1.3, - , Internet RFC 1951 (May 1996). - 1mOPTIONS0m 1m-a --ascii0m Ascii text mode: convert end-of-lines using local conventions. @@ -111,15 +105,19 @@ GZIP(1) GZIP(1) 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: @@ -128,69 +126,72 @@ GZIP(1) GZIP(1) 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. @@ -204,15 +205,28 @@ GZIP(1) GZIP(1) 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 @@ -226,8 +240,8 @@ GZIP(1) GZIP(1) 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 @@ -242,42 +256,48 @@ GZIP(1) GZIP(1) 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, 1m22m, Inter- - net RFC 1952 (May 1996). The 4mzip24m deflation format is specified in P. + ification version 4.3, 1m22m, Internet + RFC 1952 (May 1996). The 4mzip24m deflation format is specified in P. Deutsch, DEFLATE Compressed Data Format Specification version 1.3, - 1m22m, Internet RFC 1951 (May 1996). + 1m22m, 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 @@ -295,7 +315,7 @@ GZIP(1) GZIP(1) 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. @@ -324,16 +344,8 @@ GZIP(1) GZIP(1) 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 @@ -349,24 +361,25 @@ GZIP(1) GZIP(1) 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)