huschi.net

PIGZ(1)                     General Commands Manual                    PIGZ(1)

NAME
       pigz, unpigz - compress or expand files
SYNOPSIS
       pigz  [ -cdfhikKlLnNqrRtTz0..9,11 ] [ -b blocksize ] [ -p threads ] [ -S suffix
       ] [ name ...  ]
       unpigz [ -cfhikKlLnNqrRtTz ] [ -b blocksize ] [ -p threads ] [ -S  suf-
       fix ] [ name ...  ]
DESCRIPTION
       Pigz  compresses  using  threads to make use of multiple processors and
       cores.  The input is broken up into 128 KB chunks with each  compressed
       in  parallel.  The individual check value for each chunk is also calcu-
       lated in parallel.  The compressed data is written in order to the out-
       put, and a combined check value is calculated from the individual check
       values.
       The compressed data format generated is in the gzip, zlib,  or  single-
       entry zip format using the deflate compression method.  The compression
       produces partial raw deflate streams which are concatenated by a single
       write thread and wrapped with the appropriate header and trailer, where
       the trailer contains the combined check value.
       Each partial raw deflate stream is terminated by an empty stored  block
       (using  the  Z_SYNC_FLUSH option of zlib), in order to end that partial
       bit stream at a byte boundary.  That allows the partial streams  to  be
       concatenated simply as sequences of bytes.  This adds a very small four
       to five byte overhead to the output for each input chunk.
       The default input block size is 128K, but can be changed  with  the  -b
       option.  The number of compress threads is set by default to the number
       of online processors, which can be changed using the -p option.  Speci-
       fying -p 1 avoids the use of threads entirely.
       The  input blocks, while compressed independently, have the last 32K of
       the previous block loaded as a preset dictionary to preserve  the  com-
       pression  effectiveness  of  deflating in a single thread.  This can be
       turned off using the -i or --independent option, so that the blocks can
       be  decompressed independently for partial error recovery or for random
       access. This also inserts an extra  empty  block  to  flag  independent
       blocks by prefacing each with the nine-byte sequence (in hex): 00 00 FF
       FF 00 00 00 FF FF.
       Decompression can't be parallelized, at  least  not  without  specially
       prepared  deflate  streams  for that purpose.  As a result, pigz uses a
       single thread (the main thread)  for  decompression,  but  will  create
       three  other threads for reading, writing, and check calculation, which
       can speed up decompression under some circumstances.   Parallel  decom-
       pression  can  be turned off by specifying one process ( -dp 1 or -tp 1
       ).
       Compressed files can be restored to their original form using  pigz  -d
       or unpigz.

OPTIONS
       -# --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-
              pression method (best compression).  -0 is no compression.   -11
              gives  a few percent better compression at a severe cost in exe-
              cution time, using the zopfli  algorithm  by  Jyrki  Alakuijala.
              The default is -6.
       -b --blocksize mmm
              Set compression block size to mmmK (default 128KiB).
       -c --stdout --to-stdout
              Write all processed output to stdout (won't delete).
       -d --decompress --uncompress
              Decompress the compressed input.
       -f --force
              Force overwrite, compress .gz, links, and to terminal.
       -h --help
              Display a help screen and quit.
       -i --independent
              Compress blocks independently for damage recovery.
       -k --keep
              Do not delete original file after processing.
       -K --zip
              Compress to PKWare zip (.zip) single entry format.
       -l --list
              List the contents of the compressed input.
       -L --license
              Display the pigz license and quit.
       -n --no-name
              Do not store or restore file name in/from header.
       -N --name
              Store/restore file name and mod time in/from header.
       -p --processes n
              Allow up to n processes (default is the number of online proces-
              sors)
       -q --quiet --silent
              Print no messages, even on error.
       -r --recursive
              Process the contents of all subdirectories.
       -R --rsyncable
              Input-determined block locations for rsync.
       -S --suffix .sss
              Use suffix .sss instead of .gz (for compression).
       -t --test
              Test the integrity of the compressed input.
       -T --no-time
              Do not store or restore mod time in/from header.
       -v --verbose
              Provide more verbose output.
       -V --version
              Show the version of pigz. -vV also shows the zlib version.
       -z --zlib
              Compress to zlib (.zz) instead of gzip format.
       --     All arguments after "--" are treated as file  names  (for  names
              that start with "-")
       These options are unique to the -11 compression level:
       -F --first
              Do iterations first, before block split (default is last).
       -I, --iterations n
              Number of iterations for optimization (default 15).
       -M, --maxsplits n
              Maximum number of split blocks (default 15).
       -O --oneblock
              Do not split into smaller blocks (default is block splitting).
COPYRIGHT NOTICE
       This  software is provided 'as-is', without any express or implied war-
       ranty.  In no event will the author be  held  liable  for  any  damages
       arising from the use of this software.
       Copyright (C) 2007-2016 Mark Adler <madler AT alumni.edu>

                                October 1, 2016                        PIGZ(1)