man bunzip2
bzip2(1)
bzip2(1)
NAME
bzip2, bunzip2 - a block-sorting file compressor,
v1.0.2
bzcat - decompresses files to stdout
bzip2recover - recovers data from damaged bzip2
files
SYNOPSIS
bzip2 [ -cdfkqstvzVL123456789 ] [ filenames ... ]
bunzip2 [ -fkvsVL ] [ filenames ... ]
bzcat [ -s ] [ filenames ... ]
bzip2recover filename
DESCRIPTION
bzip2 compresses files using the Burrows-Wheeler
block sorting text com
pression algorithm, and Huffman coding. Compression
is generally consider
ably better than that achieved by more
conventional LZ77/LZ78-based com
pressors, and approaches the performance of the PPM
family of statistical
compressors.
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 out
put to a terminal, as this would be entirely
incomprehensible and therefore
pointless.
bunzip2 (or bzip2 -d) decompresses all specified
files. Files which were
not created by bzip2 will be detected and ignored,
and a warning issued.
bzip2 attempts to guess the filename for the
decompressed file from that of
the compressed file as follows:
filename.bz2 becomes filename
filename.bz becomes filename
filename.tbz2 becomes filename.tar
filename.tbz becomes filename.tar
anyothername becomes anyothername.out
If the file does not end in one of the recognised
endings, .bz2, .bz, .tbz2
or .tbz, bzip2 complains that it cannot guess the
name of the original
file, and uses the original name with .out appended.
As with compression, supplying no filenames causes
decompression from stan
dard input to standard output
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