bzip3(1) General Commands Manual bzip3(1)
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. The default is 16MiB.
-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. Default is to use 1 worker thread.
--rm Remove the input files after successful compression or
decompression. This is silently ignored if output is stdout.
-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, k@iczelia.net.
https://github.com/iczelia/bzip3
Thanks to: Ilya Grebnov, Benjamin Strachan, Caleb Maclennan, Ilya
Muravyov, package maintainers - Leah Neukirchen, Grigory Kirillov,
Maciej Barc, Robert Schutz, Petr Pisar, Przemyslaw Skibinski, Shun
Sakai and others. Also everyone who sent patches, helped with
portability problems, encouraged me to work on bzip3 and lent me
machines for performance tests.
SEE ALSO
bzip2(1), bz3less(1), bz3more(1), bz3grep(1), bunzip3(1)
version v1.5.4 12 September 2026 bzip3(1)
bzip3 1.5.4 - Generated Sat Sep 12 06:34:57 CDT 2026