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.TH GZIP 1
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.SH NAME
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gzip, gunzip, bzip2, bunzip2, compress, uncompress, zip, unzip \- compress and expand data
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.SH SYNOPSIS
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.B gzip
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.RB [ -cvD [ 1-9 ]]
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.RI [ file
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.BR ... ]
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.PP
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.B gunzip
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.RB [ -ctTvD ]
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.RI [ file
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.BR ... ]
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.PP
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.B bzip2
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.RB [ -cvD [ 1-9 ]]
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.RI [ file
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.BR ... ]
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.PP
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.B bunzip2
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.RB [ -cvD ]
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.RI [ file
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.BR ... ]
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.PP
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.B compress
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[
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.B -cv
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] [
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.I file
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.B ...
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]
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.PP
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.B uncompress
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[
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.B -cv
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] [
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.I file
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.B ...
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]
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.PP
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.B zip
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.RB [ -avD [ 1-9 ]]
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.RB [ -f
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.IR zipfile ]
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.I file
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.RB [ ... ]
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.PP
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.B unzip
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.RB [ -cistTvD ]
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.RB [ -f
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.IR zipfile ]
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.RI [ file
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.BR ... ]
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.SH DESCRIPTION
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.PP
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.I Gzip
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encodes files with a hybrid Lempel-Ziv 1977 and Huffman compression algorithm
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known as
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.BR deflate .
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Most of the time, the resulting file is smaller,
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and will never be much bigger.
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Output files are named by taking the last path element of each file argument
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and appending
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.BR .gz ;
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if the resulting name ends with
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.BR .tar.gz ,
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it is converted to
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.B .tgz
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instead.
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.I Gunzip
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reverses the process.
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Its output files are named by taking the last path element of each file argument,
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converting
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.B .tgz
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to
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.BR .tar.gz ,
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and stripping any
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.BR .gz ;
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the resulting name must be different from the original name.
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.PP
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.I Bzip2
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and
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.I bunzip2
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are similar in interface to
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.I gzip
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and
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.IR gunzip ,
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but use a modified Burrows-Wheeler block sorting
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compression algorithm.
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The default suffix for output files is
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.BR .bz2 ,
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with
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.B .tar.bz2
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becoming
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.BR .tbz .
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.I Bunzip2
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recognizes the extension
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.B .tbz2
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as a synonym for
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.BR .tbz .
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.PP
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.I Compress
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and
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.I uncompress
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are similar in interface to
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.I gzip
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and
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.IR gunzip ,
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but use the Lempel-Ziv-Welch compression algorithm.
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The default suffix for output files is
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.BR .Z .
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.I Compress
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is one of the oldest widespread Unix compression programs.
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.PP
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.I Zip
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encodes the named files and places the results into the archive
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.IR zipfile ,
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or the standard output if no file is given.
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.I Unzip
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extracts files from an archive created by
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.IR zip .
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If no files are named as arguments, all of files in the archive are extracted.
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A directory's name implies all recursively contained files and subdirectories.
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.I Zip
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is the
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.I "de facto"
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standard for compression on Microsoft operating systems.
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.PP
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None of these programs removes the original files.
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If the process fails, the faulty output files are removed.
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.PP
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The options are:
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.TP 0.6i
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.B -a
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Automaticialy creates directories as needed, needed for zip files
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created by broken implementations which omit directories.
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.TP
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.B -c
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Write to standard output rather than creating an output file.
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.TP
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.B -i
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Convert all archive file names to lower case.
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.TP
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.B -s
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Streaming mode.  Looks at the file data adjacent to each compressed file
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rather than seeking in the central file directory.
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This is the mode used by
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.I unzip
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if no
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.I zipfile
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is specified.
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If
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.B -s
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is given,
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.B -T
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is ignored.
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.TP
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.B -t
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List matching files in the archive rather than extracting them.
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.TP
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.B -T
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Set the output time to that specified in the archive.
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.TP
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.BR -1 " .. " -9
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Sets the compression level.
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.B -1
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is tuned for speed,
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.B -9
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for minimal output size.
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The best compromise is
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.BR -6 ,
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the default.
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.TP
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.B -v
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Produce more descriptive output.
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With
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.BR -t ,
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adds the uncompressed size in bytes and the modification time to the output.
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Without
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.BR -t ,
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prints the names of files on standard error as they are compressed or decompressed.
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.TP
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.B -D
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Produce debugging output.
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.SH SOURCE
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.B /sys/src/cmd/gzip
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.br
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.B /sys/src/cmd/bzip2
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.br
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.B /sys/src/cmd/compress
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.SH SEE ALSO
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.IR tar (1)
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.br
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"A Technique for High Performance Data Compression",
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Terry A. Welch,
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.IR "IEEE Computer" ,
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vol. 17, no. 6 (June 1984), pp. 8-19.
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.SH BUGS
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.I Unzip
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can only extract files which are uncompressed or compressed
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with the
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.B deflate
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compression scheme.  Recent zip files fall into this category.
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Very recent zip files may have tables of contents that
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.I unzip
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cannot read.  Such files are still readable by invoking
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.I unzip
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with the
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.B -s
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option.