pbzip2(1) User Commands 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

pbzip2(1)