pbzip2

pbzip2(1)                    General Commands Manual                   pbzip2(1)



NAME
       pbzip2  -  parallel bzip2 file compressor, v1.1.10

SYNOPSIS
       pbzip2 [ -123456789 ] [ -b#cdfhklm#p#qrS#tvVz ] [ filenames ...  ]

DESCRIPTION
       pbzip2 is a parallel implementation of the bzip2 block-sorting file
       compressor that uses pthreads and achieves near-linear speedup on SMP
       machines. The output of this version is fully compatible with bzip2
       v1.0.2 or newer (ie: anything compressed with pbzip2 can be decompressed
       with bzip2).

       pbzip2 should work on any system that has a pthreads compatible C++
       compiler (such as gcc). It has been tested on: Linux, Windows (cygwin),
       Solaris, Tru64/OSF1, HP-UX, and Irix.

       The default settings for pbzip2 will work well in most cases. The only
       switch you will likely need to use is -d to decompress files and -p to
       set the # of processors for pbzip2 to use if autodetect is not supported
       on your system, or you want to use a specific # of CPUs.

OPTIONS
       -b#    Where # is block size in 100k steps (default 9 = 900k)

       -c, --stdout
              Output to standard out (stdout)

       -d,--decompress
              Decompress file

       -f,--force
              Force, overwrite existing output file

       -h,--help
              Print this help message

       -k,--keep
              Keep input file, do not delete

       -l,--loadavg
              Load average determines max number processors to use

       -m#    Where # is max memory usage in 1MB steps (default 100 = 100MB)

       -p#    Where # is the number of processors (default: autodetect)

       -q,--quiet
              Quiet mode (default)

       -r,--read
              Read entire input file into RAM and split between processors

       -S#    Child thread stack size in 1KB steps (default stack size if
              unspecified)

       -t,--test
              Test compressed file integrity

       -v,--verbose
              Verbose mode

       -V     Display version info for pbzip2 then exit

       -z,--compress
              Compress file (default)

       -1,--fast ... -9,--best
              Set BWT block size to 100k .. 900k (default 900k).

       --ignore-trailing-garbage=#
              Ignore trailing garbage flag (1 - ignored; 0 - forbidden)

       If no file names are given, pbzip2 compresses or decompresses from
       standard input to standard output.

FILE SIZES
       You should be able to compress files larger than 4GB with pbzip2.

       Files that are compressed with pbzip2 are broken up into pieces and each
       individual piece is compressed.  This is how pbzip2 runs faster on
       multiple CPUs since the pieces can be compressed simultaneously.  The
       final .bz2 file may be slightly larger than if it was compressed with the
       regular bzip2 program due to this file splitting (usually less than 0.2%
       larger).  Files that are compressed with pbzip2 will also gain
       considerable speedup when decompressed using pbzip2.

       Files that were compressed using bzip2 will not see speedup since bzip2
       packages the data into a single chunk that cannot be split between
       processors.

EXAMPLES
       Example 1: pbzip2 myfile.tar

       This example will compress the file "myfile.tar" into the compressed file
       "myfile.tar.bz2". It will use the autodetected # of processors (or 2
       processors if autodetect not supported) with the default file block size
       of 900k and default BWT block size of 900k.

       Example 2: pbzip2 -b15k myfile.tar

       This example will compress the file "myfile.tar" into the compressed file
       "myfile.tar.bz2". It will use the autodetected # of processors (or 2
       processors if autodetect not supported) with a file block size of 1500k
       and a BWT block size of 900k. The file "myfile.tar" will not be deleted
       after compression is finished.

       Example 3: pbzip2 -p4 -r -5 myfile.tar second*.txt

       This example will compress the file "myfile.tar" into the compressed file
       "myfile.tar.bz2". It will use 4 processors with a BWT block size of 500k.
       The file block size will be the size of "myfile.tar" divided by 4 (# of
       processors) so that the data will be split evenly among each processor.
       This requires you have enough RAM for pbzip2 to read the entire file into
       memory for compression. Pbzip2 will then use the same options to compress
       all other files that match the wildcard "second*.txt" in that directory.

       Example 4: tar cf myfile.tar.bz2 --use-compress-prog=pbzip2
       dir_to_compress/
       Example 4: tar -c directory_to_compress/ | pbzip2 -c > myfile.tar.bz2

       These examples will compress the data being given to pbzip2 via pipe from
       TAR into the compressed file "myfile.tar.bz2".  It will use the
       autodetected # of processors (or 2 processors if autodetect not
       supported) with the default file block size of 900k and default BWT block
       size of 900k.  TAR is collecting all of the files from the
       "directory_to_compress/" directory and passing the data to pbzip2 as it
       works.

       Example 5: pbzip2 -d -m500 myfile.tar.bz2

       This example will decompress the file "myfile.tar.bz2" into the
       decompressed file "myfile.tar". It will use the autodetected # of
       processors (or 2 processors if autodetect not supported). It will use a
       maximum of 500MB of memory for decompression.  The switches -b, -r, and
       -1..-9 are not valid for decompression.

       Example 6: pbzip2 -dc myfile.tar.bz2 | tar x

       This example will decompress and untar the file "myfile.tar.bz2" piping
       the output of the decompressing pbzip2 to tar.

       Example 7: pbzip2 -c < myfile.txt > myfile.txt.bz2

       This example will read myfile.txt from standard input compressing it to
       standard output which is redirected to to myfile.txt.bz2.

SEE ALSO
       bzip2(1) gzip(1) lzip(1) rzip(1) zip(1)

AUTHOR
       Jeff Gilchrist

       http://compression.ca



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