GZIP(1)                                                   GZIP(1)

     NAME
          gzip, gunzip, bzip2, bunzip2, compress, uncompress, zip,
          unzip - compress and expand data

     SYNOPSIS
          gzip [-cvD[1-9]] [file ...]

          gunzip [-ctTvD] [file ...]

          bzip2 [-cvD[1-9]] [file ...]

          bunzip2 [-cvD] [file ...]

          compress [ -cv ] [ file ... ]

          uncompress [ -cv ] [ file ... ]

          zip [-avD[1-9]] [-f zipfile] file [...]

          unzip [-cistTvD] [-f zipfile] [file ...]

     DESCRIPTION
          Gzip encodes files with a hybrid Lempel-Ziv 1977 and Huffman
          compression algorithm known as deflate.  Most of the time,
          the resulting file is smaller, and will never be much big-
          ger.  Output files are named by taking the last path element
          of each file argument and appending .gz; if the resulting
          name ends with .tar.gz, it is converted to .tgz instead.
          Gunzip reverses the process.  Its output files are named by
          taking the last path element of each file argument, convert-
          ing .tgz to .tar.gz, and stripping any .gz; the resulting
          name must be different from the original name.

          Bzip2 and bunzip2 are similar in interface to gzip and
          gunzip, but use a modified Burrows-Wheeler block sorting
          compression algorithm.  The default suffix for output files
          is .bz2, with .tar.bz2 becoming .tbz.  Bunzip2 recognizes
          the extension .tbz2 as a synonym for .tbz.

          Compress and uncompress are similar in interface to gzip and
          gunzip, but use the Lempel-Ziv-Welch compression algorithm.
          The default suffix for output files is .Z.  Compress is one
          of the oldest widespread Unix compression programs.

          Zip encodes the named files and places the results into the
          archive zipfile, or the standard output if no file is given.
          Unzip extracts files from an archive created by zip. If no
          files are named as arguments, all of files in the archive
          are extracted.  A directory's name implies all recursively
          contained files and subdirectories.  Zip is the de facto

     GZIP(1)                                                   GZIP(1)

          standard for compression on Microsoft operating systems.

          None of these programs removes the original files.  If the
          process fails, the faulty output files are removed.

          The options are:

          -a    Automaticialy creates directories as needed, needed
                for zip files created by broken implementations which
                omit directories.

          -c    Write to standard output rather than creating an out-
                put file.

          -i    Convert all archive file names to lower case.

          -s    Streaming mode.  Looks at the file data adjacent to
                each compressed file rather than seeking in the cen-
                tral file directory.  This is the mode used by unzip
                if no zipfile is specified.  If -s is given, -T is
                ignored.

          -t    List matching files in the archive rather than
                extracting them.

          -T    Set the output time to that specified in the archive.

          -1 .. -9
                Sets the compression level.  -1 is tuned for speed, -9
                for minimal output size.  The best compromise is -6,
                the default.

          -v    Produce more descriptive output.  With -t, adds the
                uncompressed size in bytes and the modification time
                to the output.  Without -t, prints the names of files
                on standard error as they are compressed or decom-
                pressed.

          -D    Produce debugging output.

     SOURCE
          /sys/src/cmd/gzip
          /sys/src/cmd/bzip2
          /sys/src/cmd/compress

     SEE ALSO
          tar(1)
          "A Technique for High Performance Data Compression", Terry
          A. Welch, IEEE Computer, vol. 17, no. 6 (June 1984), pp. 8-
          19.

     BUGS

     GZIP(1)                                                   GZIP(1)

          Unzip can only extract files which are uncompressed or com-
          pressed with the deflate compression scheme.  Recent zip
          files fall into this category.  Very recent zip files may
          have tables of contents that unzip cannot read.  Such files
          are still readable by invoking unzip with the -s option.