1PIGZ(1) General Commands Manual PIGZ(1)
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6 pigz, unpigz - compress or expand files
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9 pigz [ -cdfhikKlLmMnNqrRtz0..9,11 ] [ -b blocksize ] [ -p threads ] [ -S suffix
10 ] [ name ... ]
11 unpigz [ -cfhikKlLmMnNqrRtz ] [ -b blocksize ] [ -p threads ] [ -S suf‐
12 fix ] [ name ... ]
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15 Pigz compresses using threads to make use of multiple processors and
16 cores. The input is broken up into 128 KB chunks with each compressed
17 in parallel. The individual check value for each chunk is also calcu‐
18 lated in parallel. The compressed data is written in order to the out‐
19 put, and a combined check value is calculated from the individual check
20 values.
21 The compressed data format generated is in the gzip, zlib, or single-
23 entry zip format using the deflate compression method. The compression
24 produces partial raw deflate streams which are concatenated by a single
25 write thread and wrapped with the appropriate header and trailer, where
26 the trailer contains the combined check value.
27 Each partial raw deflate stream is terminated by an empty stored block
29 (using the Z_SYNC_FLUSH option of zlib), in order to end that partial
30 bit stream at a byte boundary. That allows the partial streams to be
31 concatenated simply as sequences of bytes. This adds a very small four
32 to five byte overhead to the output for each input chunk.
33 The default input block size is 128K, but can be changed with the -b
35 option. The number of compress threads is set by default to the number
36 of online processors, which can be changed using the -p option. Speci‐
37 fying -p 1 avoids the use of threads entirely.
38 The input blocks, while compressed independently, have the last 32K of
40 the previous block loaded as a preset dictionary to preserve the com‐
41 pression effectiveness of deflating in a single thread. This can be
42 turned off using the -i or --independent option, so that the blocks can
43 be decompressed independently for partial error recovery or for random
44 access. This also inserts an extra empty block to flag independent
45 blocks by prefacing each with the nine-byte sequence (in hex): 00 00 FF
46 FF 00 00 00 FF FF.
47 Decompression can't be parallelized, at least not without specially
49 prepared deflate streams for that purpose. As a result, pigz uses a
50 single thread (the main thread) for decompression, but will create
51 three other threads for reading, writing, and check calculation, which
52 can speed up decompression under some circumstances. Parallel decom‐
53 pression can be turned off by specifying one process ( -dp 1 or -tp 1
54 ).
55 All options on the command line are processed before any names are pro‐
57 cessed. If no names are provided on the command line, or if "-" is
58 given as a name (but not after "--"), then the input is taken from
59 stdin.
60 Compressed files can be restored to their original form using pigz -d
62 or unpigz.
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66 -# --fast --best
67 Regulate the speed of compression using the specified digit #,
68 where -1 or --fast indicates the fastest compression method
69 (less compression) and -9 or --best indicates the slowest com‐
70 pression method (best compression). -0 is no compression. -11
71 gives a few percent better compression at a severe cost in exe‐
72 cution time, using the zopfli algorithm by Jyrki Alakuijala.
73 The default is -6.
74 -b --blocksize mmm
76 Set compression block size to mmmK (default 128KiB).
77 -c --stdout --to-stdout
79 Write all processed output to stdout (won't delete).
80 -d --decompress --uncompress
82 Decompress the compressed input.
83 -f --force
85 Force overwrite, compress .gz, links, and to terminal.
86 -h --help
88 Display a help screen and quit.
89 -i --independent
91 Compress blocks independently for damage recovery.
92 -k --keep
94 Do not delete original file after processing.
95 -K --zip
97 Compress to PKWare zip (.zip) single entry format.
98 -l --list
100 List the contents of the compressed input.
101 -L --license
103 Display the pigz license and quit.
104 -m --no-time
106 Do not store or restore the modification time. -Nm will store or
107 restore the name, but not the modification time. Note that the
108 order of the options is important.
109 -M --time
111 Store or restore the modification time. -nM will store or
112 restore the modification time, but not the name. Note that the
113 order of the options is important.
114 -n --no-name
116 Do not store or restore the file name or the modification time.
117 This is the default when decompressing. When the file name is
118 not restored from the header, the name of the compressed file
119 with the suffix stripped is the name of the decompressed file.
120 When the modification time is not restored from the header, the
121 modification time of the compressed file is used (not the cur‐
122 rent time).
123 -N --name
125 Store or restore both the file name and the modification time.
126 This is the default when compressing.
127 -p --processes n
129 Allow up to n processes (default is the number of online proces‐
130 sors)
131 -q --quiet --silent
133 Print no messages, even on error.
134 -r --recursive
136 Process the contents of all subdirectories.
137 -R --rsyncable
139 Input-determined block locations for rsync.
140 -S --suffix .sss
142 Use suffix .sss instead of .gz (for compression).
143 -t --test
145 Test the integrity of the compressed input.
146 -v --verbose
148 Provide more verbose output.
149 -V --version
151 Show the version of pigz. -vV also shows the zlib version.
152 -z --zlib
154 Compress to zlib (.zz) instead of gzip format.
155 -- All arguments after "--" are treated as file names (for names
157 that start with "-")
158 These options are unique to the -11 compression level:
160 -F --first
162 Do iterations first, before block split (default is last).
163 -I, --iterations n
165 Number of iterations for optimization (default 15).
166 -J, --maxsplits n
168 Maximum number of split blocks (default 15).
169 -O --oneblock
171 Do not split into smaller blocks (default is block splitting).
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174 This software is provided 'as-is', without any express or implied war‐
175 ranty. In no event will the author be held liable for any damages
176 arising from the use of this software.
177 Copyright (C) 2007-2017 Mark Adler <madler@alumni.caltech.edu>
179 December 26, 2017 PIGZ(1)