bzip2
More at wikipedia. See the link at the bottom too. The command-line options are similar to those of GNU gzip.
Files on the command line (or expanded by globing) are replaced by a compressed version with the name suffixed by
Files are not over-written, specify Piping is done if no file names are specified reading from standard input to writing to standard output (usefull to pipe elsewhere).
Decompresses specified files, unless they were not created by bzip2 which will be skipped with a warning.
If the file does not end in a recognised ending, .bz2, .bz, .tbz2 or .tbz, bzip2 warns that it cannot
determine the name of the original file, and uses the original name with Given the concatenation of two or more compressed files produces the concatenation of the corresponding uncompressed files.
Integrity testing (
files re output to the standard output by using
Return values:
zip warning: missing end signature--probably not a zip file (did you zip warning: remember to use binary mode when you transferred it?) zip warning: (if you are trying to read a damaged archive try -F) zip error: Zip file structure invalid (auth.log.0.bz2)
|
bzip2, bunzip2 and bzcat are the same program, and the decision about what actions to take is done on the basis of which name is used.
Author Julian Seward, jsewardbzip.org. bzip.org:
--list
, -l
gzip -l *gz compressed uncompressed ratio uncompressed_name 20 0 0.0% smother.diske- 20 0 0.0% smother.diskf- 20 0 0.0% smother.diskg- 20 0 0.0% smother.diskh- 798830592 3596346423 77.8% smother_wd0e 798830672 3596346423 77.8% (totals)with
--verbose
gzip -lv *gz method crc date time compressed uncompressed ratio uncompressed_name defla 00000000 Sep 1 15:00 20 0 0.0% smother.diske- defla 00000000 Sep 1 15:01 20 0 0.0% smother.diskf- defla 00000000 Sep 1 15:01 20 0 0.0% smother.diskg- defla 00000000 Sep 1 15:01 20 0 0.0% smother.diskh- defla dbd673f2 Sep 1 16:09 798830592 3596346423 77.8% smother_wd0e 798830672 3596346423 77.8% (totals)The uncompressed size is given as
-1
for files not in gzip
format, such as compressed .Z
files. zcat file.Z | wc -c
--quiet
,.
bzip2: xxx.zip: bad magic number (file not created by bzip2) You can use the `bzip2recover' program to attempt to recover data from undamaged sections of corrupted files. > echo $? 2 > file 3.31.1_H+2.zip xxx.zip: Zip archive data, at least v2.0 to extract, compression method=storeOr try
gzip
.
--decompress --uncompress -d
-r --recursive Travel the directory structure recursively. |
| -S suf --suffix suf Suffix | suf A null suffix decompresses all given files as in: gunzip -S "" * (*.* for MSDOS) -t --test Test the compressed file
| --quiet -q Suppress warning messages.
| | -v --verbose Display the name and percentage reduction for each file on stderr. | --no-name -n When compressing, do not save the original name and time stamp . | The original name is saved if the name had to be truncated.
When decompressing, do not restore the original name. --name -N
When compressing, save the original name and time stamp (default). | When decompressing, restore the original name and time stamp. --stdout --to-stdout -c output on standard output. Do not change the input file. | WIth several input files, the output consists of a sequence of independently compressed members. For best compression, concatenate input files before compressing them. --fast --best -n
Specify speed/compression tradeoff | --fast or -1 fastest / less compression -6 biased towards high compression at expense of speed.Default --best or -9 slowest / more compression --force -f For a file with multiple links or | the corresponding file exists or if the data is from/to a terminal.
If the input is not in a recognized by zcat Behave as | cat . br>
If --force is not given, and
not running in the background, prompt to verify if a file should be overwritten.
--help -h
--version -V
--license -L Display the | gzip license then quit.
|
Find all gzip
files in the current directory and subdirectories, and extract them in place without
destroying the original:
find . -name '*.gz' -print | sed 's/^\(.*\)[.]gz$/gunzip < "&" > "\1"/' | sh
Best compression can be obtained if members are decompressed and then recompressed in a single step.
Concatenating gzip
files:
gzip --to-stdout file1 > foo.gz gzip --to-stdout file2 >> foo.gz
gunzip --to-stdout foo
is equivalent to cat file1 file2
To recompress concatenated files to get better compression: zcat old.gz | gzip > new.gz
A compressed file with several members, the uncompressed
size and CRC reported by --list
to the last member only.
To display the uncompressed size for all members, use:
zcat file.gz | wc -c
Create an archive with multiple members use an archiver such as tar
or zip
.
GNU tar
supports -z
to invoke gzip
.
gzip
is a complement to tar
, not a replacement.
$GZIP
default options, interpreted first and overwritten by command line parameters. for sh: GZIP="-8v --name"; export GZIP for csh: setenv GZIP "-8v --name" for MSDOS: set GZIP=-8v --name
gzip
on tapes
When writing compressed data to a tape, pad the output with zeroes 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, --quiet
to suppress the warning.
The original documentation containg supstantial discussions related to legacy versions running on VM, MSDOS... which had file systems with sever limitations including kength of filename.
gzip
reduces the size using Lempel-Ziv coding
(LZ77) replacing a file by one with the extension .gz
.
If no files are specified or if a name is -
standard input is compressed to the standard output.
Compress regular files ( symbolic links are ignored).
gzip
saves the original name and timestamp in the compressed file and uses it when decompressing the with -N
.
gunzip
takes a list of files on the command line and replaces each file whose name ends with .gz
,
zcat
is identical to gunzip -c
with a .gz
suffix or not.
Apple gzip 272.250.1 usage: gzip [-123456789acdfhklLNnqrtVv] [-S .suffix] [www.bzip.org[ ...]] -1 --fast fastest (worst) compression -2 .. -8 set compression level -9 --best best (slowest) compression -c --stdout write to stdout, keep original files --to-stdout -d --decompress uncompress files --uncompress -f --force force overwriting & compress links -k --keep don't delete input files during operation -l --list list compressed file contents -N --name save or restore original file name and time stamp -n --no-name don't save original file name or time stamp -r --recursive recursively compress files in directories -q --quiet output no warnings -S .suf use suffix .suf instead of .gz --suffix .suf -t --test test compressed file -V --version display program version -v --verbose print extra statistics -h --help display this help As on Monterey: gzip -V Apple gzip 353.100.22 gzip --license Apple gzip 353.100.22 (based on FreeBSD gzip 20190107, NetBSD gzip 20150113) Copyright (c) 1997, 1998, 2003, 2004, 2006 Matthew R. Green …