bzip2

Compress or decompress named file(s).

Syntax
      bzip2 [ -cdfkqstvzVL123456789 ] [ filenames ... ]

      bunzip2 [ -fkvsVL ] [ filenames ... ]

      bzcat [ -s ] [ filenames ... ]

      bzip2recover filename

Key
   -c --stdout      Compress or decompress to standard output.

   -d --decompress  Force decompression. bzip2, bunzip2 and bzcat are really the same program,
                    and the decision about what actions to take is done on the basis of which
                    name is used. This flag overrides that mechanism, and forces bzip2 to decompress.

   -z --compress    The complement to -d: forces compression, regardless of the invokation name.

   -t --test        Check integrity of the specified file(s), but don't decompress them.
                    This really performs a trial decompression and throws away the result.

   -f --force       Force overwrite of output files. Normally, bzip2 will not overwrite existing
                    output files. Also forces bzip2 to break hard links to files, which it otherwise
                    wouldn't do. bzip2 normally declines to decompress files which don't have the
                    correct magic header bytes. If forced (-f), however, it will pass such files
                    through unmodified. This is how GNU gzip behaves.

   -k --keep        Keep (don't delete) input files during compression or decompression.

   -s --small       Reduce memory usage, for compression, decompression and testing. Files are
                    decompressed and tested using a modified algorithm which only requires 2.5 bytes
                    per block byte. This means any file can be decompressed in 2300k of memory, albeit
                    at about half the normal speed. During compression, -s selects a block size of
                    200k, which limits memory use to around the same figure, at the expense of your
                    compression ratio. In short, if your machine is low on memory (8 megabytes or less),
                    use -s for everything.

   -q --quiet       Suppress non-essential warning messages. Messages pertaining to I/O errors and
                    other critical events will not be suppressed.

   -v --verbose     Verbose mode -- show the compression ratio for each file processed. Further -v's
                    increase the verbosity level, spewing out lots of information which is primarily
                    of interest for diagnostic purposes.

   -L --license
   -V --version     Display the software version, license terms and conditions.

   -1 (or --fast) to -9 (or -best)
                    Set the block size to 100 k, 200 k ... 900 k when compressing. Has no effect when
                    decompressing. The --fast and --best aliases are primarily for GNU gzip
                    compatibility. In particular, --fast doesn't make things significantly faster.
                    And --best merely selects the default behaviour.

   --               Treats 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,
                    for example: bzip2 -- -myfilename.

   --repetitive-fast, --repetitive-best
                    These flags are redundant in versions 0.9.5 and above. They provided some coarse
                    control over the behaviour of the sorting algorithm in earlier versions, bzip now
                    has an improved algorithm which renders these flags irrelevant.

bzip2 compresses files using the Burrows-Wheeler block sorting text compression algorithm, and Huffman coding.
The command-line options are deliberately very similar to those of GNU gzip, but they are not identical.

bzip2 expects a list of file names to accompany the command-line flags. Each file is replaced by a compressed version of itself, with the name original_name.bz2. Each compressed file has the same modification date, permissions, and, when possible, ownership as the corresponding original, so that these properties can be correctly restored at decompression time.

File name handling is naive in the sense that there is no mechanism for preserving original file names, permissions, ownerships or dates in filesystems which lack these concepts, or have serious file name length restrictions, such as MS-DOS.

bzip2 and bunzip2 will by default not overwrite existing files. If you want this to happen, specify the -f flag.
If no file names are specified, bzip2 compresses from standard input to standard output. In this case, bzip2 will decline to write compressed output to a terminal, as this would be entirely incomprehensible and therefore pointless.

Website: bzip.org

Examples

Compress the file mountetna.csv and replace it with a compressed version named mountetna.csv.bz2

$ bzip2 mountetna.csv

Compress the file mountetna.csv, keep the uncompressed version and create the new file by redirecting standard out:

$ bzip2 mountetna.csv > mountetna.csv.bz2

Combine a set of mp3 music files into one file with tar and then zip the result with bzip2:

$ tar -cf music.tar miles.mp3 chet.mp3 charlie.mp3
$ bzip2 music.tar

The same as above but in one step by using the tar -j option:

$ tar -cjf music.tar.bz2 miles.mp3 chet.mp3 charlie.mp3

“What is Art, Sir, but Nature concentrated?” ~ Honoré de Balzac (Qu'est-ce que l'Art, monsieur?C'est la Nature concentrée.)

Related:

gzip - Compress or decompress named file(s)
tar - Store, list or extract files in an archive


© Copyright SS64.com 1999-2013
Some rights reserved