Ubuntu Manpage: bzip3 - an efficient statistical file compressor and spiritual successor to bzip2

NAME

       bzip3 - an efficient statistical file compressor and spiritual successor to bzip2

SYNOPSIS

       bzip3 [ -BbcdehftV ] [ filenames ...  ]

       bz3cat is equivalent to bzip3 -dc

       bunzip3 is equivalent to bzip3 -d

DESCRIPTION

       Compress  or  decompress  a  file  using  run  length encoding and Lempel Ziv prediction, followed by the
       Burrows-Wheeler transform and arithmetic coding.  bzip3, like its ancestor bzip2, excels  at  compressing
       text or source code.

       The command-line options are deliberately very similar to those of bzip2, but they are not identical.

       bzip3 expects at most two filenames intertwined with flags.  bzip3 will by default not overwrite existing
       files.  If this behaviour is intended, use the -f flag.

       If  no  file names are specified, bzip3 will compress from standard input to standard output, refusing to
       output binary data to a terminal. The -e flag (encode) is implied.

       bunzip3 (or, bzip3 -d equivalently) decompresses  data  from  standard  input  to  the  standard  output,
       refusing to read from a terminal.

       If  two files are specified, the first one is used in place of standard input, and the second one is used
       in place of standard output.

       If the -c flag is present, bzip3 will read from the specified file and output  data  to  standard  output
       instead.  Otherwise,  if decoding, bzip3 will try to guess the decompressed filename by removing the .bz3
       extension. If not present, an error will be reported. If encoding, the output filename will be  generated
       by appending the .bz3 extension to the input filename.

OPTIONS

-B --batch
Enable batch mode. By default, bzip3 will error if more than two files are passed, and the two
files specified are always treated as input and output. The batch mode makes bzip3 treat every
file as input, so for example bzip3 -Bd *.bz3 will decompress all .bz3 files in the current
directory.

-b --block N
Set the block size to N mebibytes. The minimum is 1MiB, the maximum is 511MiB.

-c --stdout
Force writing output data to the standard output if one file is specified.

-d --decode
Force decompression.

-e/-z --encode
Force compression (default behaviour).

-f --force
Overwrite existing files.

-h --help
Display a help message and exit.

-j --jobs N
Set the amount of parallel worker threads that process one block each.

-k --keep
Keep (don't delete) the input files. Set by default, provided only for compatibility with other
compressors.

-v --verbose
Set verbose output mode to see compression statistics.

-V --version
Display version information and exit.

-t --test
Verify the validity of compressed blocks.

-- Treat all subsequent arguments as file names, even if they start with a dash. This is so you can
handle files with names beginning with a dash.

FILE FORMAT

       Compression is performed as long as the input block is longer than 64 bytes. Otherwise, it's coded  as  a
       literal  block.  In  all  other  cases,  the  compressed data is written to the file. The file format has
       constant overhead of 9 bytes per file and from 9 to 17 bytes per block. Random  data  is  coded  so  that
       expansion is generally under 0.8%.

       bzip3  uses  32-bit  CRC  to ensure that the decompressed version of a file is identical to the original.
       This guards against corruption of the compressed data.

MEMORY MANAGEMENT

       The -b flag sets the block size in mebibytes (MiB). The default is 16 MiB. Compression and  decompression
       memory usage can be estimated as:

              6 x block size

       Larger block sizes usually give rapidly diminishing returns.  It is also important to appreciate that the
       decompression memory requirement is set at compression time by the choice of block size.  In general, try
       and  use  the largest block size memory constraints allow, since that maximises the compression achieved.
       Compression and decompression speed are virtually unaffected by block size.

AUTHOR

       Kamila Szewczyk, kspalaiologos@gmail.com.

       https://github.com/kspalaiologos/bzip3

       Thanks to: Ilya Grebnov, Benjamin Strachan, Caleb Maclennan, Ilya Muravyov, package  maintainers  -  Leah
       Neukirchen,  Grigory Kirillov, Maciej Barc, Robert Schutz, Petr Pisar, and others. Also everyone who sent
       patches, helped with portability problems, encouraged me to work  on  bzip3  and  lent  me  machines  for
       performance tests.