-GZIP(1) GZIP(1)
+GZIP(1) General Commands Manual GZIP(1)
-NAME
+1mNAME0m
gzip, gunzip, zcat - compress or expand files
-SYNOPSIS
- gzip [ -acdfhlLnNrtvV19 ] [-S suffix] [ name ... ]
- gunzip [ -acfhlLnNrtvV ] [-S suffix] [ name ... ]
- zcat [ -fhLV ] [ name ... ]
+1mSYNOPSIS0m
+ 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 ]
-DESCRIPTION
- Gzip reduces the size of the named files using Lempel-Ziv coding
+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 .gz, while keeping the same ownership modes, access and modi-
- fication times. (The default extension is -gz for VMS, z for 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. Gzip will only attempt to compress regular files. In particu-
- lar, it will ignore symbolic links.
-
- If the compressed file name is too long for its file system, gzip trun-
- cates it. Gzip attempts to truncate only the parts of the file name
+ 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
longer than 3 characters. (A part is delimited by dots.) If the name
consists of small parts only, the longest parts are truncated. For
example, if file names are limited to 14 characters, gzip.msdos.exe is
compressed to gzi.msd.exe.gz. Names are not truncated on systems which
do not have a limit on file name length.
- By default, gzip keeps the original file name and timestamp in the com-
- pressed file. These are used when decompressing the file with the -N
+ 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 gzip -d
- or gunzip or zcat. If the original name saved in the compressed file
+ Compressed files can be restored to their original form using 4mgzip24m 4m-d0m
+ 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.
- gunzip takes a list of files on its command line and replaces each file
+ 4mgunzip24m takes a list of files on its command line and replaces each file
whose name ends with .gz, -gz, .z, -z, or _z (ignoring case) and which
begins with the correct magic number with an uncompressed file without
- the original extension. gunzip also recognizes the special extensions
- .tgz and .taz as shorthands for .tar.gz and .tar.Z respectively. When
- compressing, gzip uses the .tgz extension if necessary instead of trun-
- cating a file with a .tar extension.
-
- gunzip can currently decompress files created by gzip, zip, compress,
- compress -H or pack. The detection of the input format is automatic.
- When using the first two formats, gunzip checks a 32 bit CRC. For pack,
- gunzip checks the uncompressed length. The standard compress format was
- not designed to allow consistency checks. However gunzip 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 uncompress does not complain. This generally means that the
- standard uncompress 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.
-
- Files created by zip can be uncompressed by gzip only if they have a
+ the original extension. 4mgunzip24m also recognizes the special extensions
+ 1m.tgz 22mand 1m.taz 22mas shorthands for 1m.tar.gz 22mand 1m.tar.Z 22mrespectively. When
+ 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 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 zip file with a single member, use a command like gunzip
- <foo.zip or gunzip -S .zip foo.zip. To extract zip files with several
- members, use unzip instead of gunzip.
+ 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 4mgunzip24m.
- zcat is identical to gunzip -c. (On some systems, zcat may be
- installed as gzcat to preserve the original link to compress.) zcat
+ 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. zcat will
+ input and writes the uncompressed data on standard output. 4mzcat24m will
uncompress files that have the correct magic number whether they have a
- .gz suffix or not.
+ 1m.gz 22msuffix or not.
- Gzip uses the Lempel-Ziv algorithm used in zip and PKZIP. The amount
+ 4mGzip24m uses the Lempel-Ziv algorithm used in 4mzip24m and PKZIP. The amount
of compression obtained depends on the size of the input and the dis-
tribution of common substrings. Typically, text such as source code or
English is reduced by 60-70%. Compression is generally much better
- than that achieved by LZW (as used in compress), Huffman coding (as
- used in pack), or adaptive Huffman coding (compact).
+ than that achieved by LZW (as used in 4mcompress24m), Huffman coding (as
+ used in 4mpack24m), or adaptive Huffman coding (4mcompact24m).
Compression is always performed, even if the compressed file is
slightly larger than the original. The worst case expansion is a few
bytes for the gzip file header, plus 5 bytes every 32K block, or an
expansion ratio of 0.015% for large files. Note that the actual number
- of used disk blocks almost never increases. gzip preserves the mode,
+ of used disk blocks almost never increases. 4mgzip24m preserves the mode,
ownership and timestamps of files when compressing or decompressing.
- The gzip 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 zip 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).
-
-OPTIONS
- -a --ascii
- Ascii text mode: convert end-of-lines using local conventions.
- This option is supported only on some non-Unix systems. For
+1mOPTIONS0m
+ 1m-a --ascii0m
+ Ascii text mode: convert end-of-lines using local conventions.
+ This option is supported only on some non-Unix systems. For
MSDOS, CR LF is converted to LF when compressing, and LF is con-
verted to CR LF when decompressing.
- -c --stdout --to-stdout
- Write output on standard output; keep original files unchanged.
- If there are several input files, the output consists of a
- sequence of independently compressed members. To obtain better
- compression, concatenate all input files before compressing
+ 1m-c --stdout --to-stdout0m
+ Write output on standard output; keep original files unchanged.
+ If there are several input files, the output consists of a
+ sequence of independently compressed members. To obtain better
+ compression, concatenate all input files before compressing
them.
- -d --decompress --uncompress
+ 1m-d --decompress --uncompress0m
Decompress.
- -f --force
+ 1m-f --force0m
Force compression or decompression even if the file has multiple
- links or the corresponding file already exists, or if the com-
+ 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 gzip, and if the option
- --stdout is also given, copy the input data without change to
- the standard output: let zcat behave as cat. If -f is not
- given, and when not running in the background, gzip prompts to
+ 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 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.
- -h --help
+ 1m-h --help0m
Display a help screen and quit.
- -l --list
+ 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:
compressed size: size of the compressed file
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
files is also displayed, unless some sizes are unknown. With
--quiet, the title and totals lines are not displayed.
- -L --license
- Display the gzip license and quit.
+ 1m-L --license0m
+ Display the 4mgzip24m license and quit.
- -n --no-name
- When compressing, do not save the original file name and time
+ 1m-n --no-name0m
+ 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 gzip suffix from
- the compressed file name) and do not restore the original time
+ 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.
- -N --name
- When compressing, always save the original file name and time
+ 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.
+ 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.
- -q --quiet
+ 1m-q --quiet0m
Suppress all warnings.
- -r --recursive
+ 1m-r --recursive0m
Travel the directory structure recursively. If any of the file
- names specified on the command line are directories, gzip will
+ 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 gunzip ).
+ there (or decompress them in the case of 4mgunzip24m ).
- -S .suf --suffix .suf
- Use suffix .suf instead of .gz. Any suffix can be given, but
- suffixes other than .z and .gz should be avoided to avoid confu-
- sion when files are transferred to other systems. A null suffix
- forces gunzip to try decompression on all given files regard-
- less of suffix, as in:
+ 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
+ other systems.
- gunzip -S "" * (*.* for MSDOS)
+ 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.
- Previous versions of gzip used the .z suffix. This was changed
- to avoid a conflict with pack(1).
+ 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.
- -t --test
+ 1m-t --test0m
Test. Check the compressed file integrity.
- -v --verbose
+ 1m-v --verbose0m
Verbose. Display the name and percentage reduction for each file
compressed or decompressed.
- -V --version
+ 1m-V --version0m
Version. Display the version number and compilation options then
quit.
- -# --fast --best
- Regulate the speed of compression using the specified digit #,
- where -1 or --fast indicates the fastest compression method
- (less compression) and -9 or --best indicates the slowest com-
+ 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
- level is -6 (that is, biased towards high compression at expense
+ level is 1m-6 22m(that is, biased towards high compression at expense
of speed).
-ADVANCED USAGE
- Multiple compressed files can be concatenated. In this case, gunzip
+ 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
will extract all members at once. For example:
gzip -c file1 > foo.gz
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.
-ENVIRONMENT
- The environment variable GZIP can hold a set of default options for
- gzip. 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
+1mENVIRONMENT0m
+ 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.
- 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.
+ 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:
-SEE ALSO
+ #! /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 gzip 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 zip 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).
+ The 4mgzip24m file format is specified in P. Deutsch, GZIP file format spec-
+ 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<https://www.ietf.org/rfc/rfc1951.txt>22m, Internet RFC 1951 (May 1996).
-DIAGNOSTICS
+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.
- file: not in gzip format
- The file specified to gunzip has not been compressed.
+ 4mfile24m: not in gzip format
+ The file specified to 4mgunzip24m has not been compressed.
- file: Corrupt input. Use zcat to recover some data.
+ 4mfile24m: Corrupt input. Use zcat to recover some data.
The compressed file has been damaged. The data up to the point
of failure can be recovered using
- zcat file > recover
+ zcat 4mfile24m > recover
- file: compressed with xx bits, can only handle yy bits
- File was compressed (using LZW) by a program that could deal
- with more bits than the decompress code on this machine. Recom-
+ 4mfile24m: compressed with 4mxx24m bits, can only handle 4myy24m bits
+ 4mFile24m was compressed (using LZW) by a program that could deal
+ with more 4mbits24m than the decompress code on this machine. Recom-
press the file with gzip, which compresses better and uses less
memory.
- file: 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.
- file already exists; do you wish to overwrite (y or n)?
+ 4mfile24m already exists; do you wish to overwrite (y or n)?
Respond "y" if you want the output file to be replaced; "n" if
not.
A SIGSEGV violation was detected which usually means that the
input file has been corrupted.
- xx.x% Percentage of the input saved by compression.
- (Relevant only for -v and -l.)
+ 4mxx.x%24m Percentage of the input saved by compression.
+ (Relevant only for 1m-v 22mand 1m-l22m.)
-- not a regular file or directory: ignored
When the input file is not a regular file or directory, (e.g. a
symbolic link, socket, FIFO, device file), it is left unaltered.
- -- has xx other links: unchanged
- The input file has links; it is left unchanged. See ln(1) for
- more information. Use the -f flag to force compression of multi-
+ -- has 4mxx24m other links: unchanged
+ The input file has links; it is left unchanged. See 4mln24m(1) for
+ more information. Use the 1m-f 22mflag to force compression of multi-
ply-linked files.
-CAVEATS
- When writing compressed data to a tape, it is generally necessary to
- pad the output with zeroes up to a block boundary. When the data is
- read and the whole block is passed to gunzip for decompression, gunzip
- 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 GZIP environment
- 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.)
-
-BUGS
- The gzip format represents the input size modulo 2^32, so the --list
- option reports incorrect uncompressed sizes and compression ratios for
- uncompressed files 4 GB and larger. To work around this problem, you
- can use the following command to discover a large uncompressed file's
+1mCAVEATS0m
+ When writing compressed data to a tape, it is generally necessary to
+ 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 can use the --quiet option to sup-
+ press the warning.
+
+1mBUGS0m
+ The gzip format represents the input size modulo 2^32, so the --list
+ option reports incorrect uncompressed sizes and compression ratios for
+ uncompressed files 4 GB and larger. To work around this problem, you
+ can use the following command to discover a large uncompressed file's
true size:
zcat file.gz | wc -c
- The --list option reports sizes as -1 and crc as ffffffff if the com-
+ The --list option reports sizes as -1 and crc as ffffffff if the com-
pressed file is on a non seekable media.
- In some rare cases, the --best option gives worse compression than the
- default compression level (-6). On some highly redundant files, com-
- press compresses better than gzip.
+ 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 4mgzip24m.
-COPYRIGHT NOTICE
- Copyright (C) 1998, 1999, 2001, 2002 Free Software Foundation, Inc.
+1mCOPYRIGHT NOTICE0m
+ 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
projects / debian / gzip / blobdiff