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COMPACT(1)							    COMPACT(1)

NAME
       compact, uncompact, ccat - compress and uncompress files, and cat them

SYNOPSIS
       compact [ -v ] [ name ... ]
       uncompact [ -v ] [ name ...  ]
       ccat [ -v ] [ file ... ]

DESCRIPTION
       Compact	compresses the named files using an adaptive Huffman code.  If
       no file names are given, the standard input is compacted to  the	 stan‐
       dard  output.   Compact	operates as an on-line algorithm.  Each time a
       byte is read, it is encoded immediately according to the current prefix
       code.   This code is an optimal Huffman code for the set of frequencies
       seen so far.  It is unnecessary to prepend a decoding tree to the  com‐
       pressed	file since the encoder and the decoder start in the same state
       and stay synchronized.  Furthermore, compact and uncompact can  operate
       as filters.  In particular,

	    ... | compact | uncompact | ...

       operates as a (very slow) no-op.

       When  an argument file is given, it is compacted and the resulting file
       is placed in file.C; file is unlinked.  The first two bytes of the com‐
       pacted  file  code  the	fact that the file is compacted.  This code is
       used to prohibit recompaction.

       The amount of compression to be expected depends on the	type  of  file
       being  compressed.  Typical values of compression are: Text (38%), Pas‐
       cal Source (43%), C Source (36%) and Binary (19%).   These  values  are
       the percentages of file bytes reduced.

       Uncompact restores the original file from a file compressed by compact.
       If no file names are given, the standard input is  uncompacted  to  the
       standard output.

       Ccat  cats the original file from a file compressed by compact, without
       uncompressing the file (it is just a shell  script  which  directs  the
       uncompacted output to the standard output).

       Compact,	 uncompact, and ccat normally do their work silently.  If a -v
       flag is supplied, compact will report the  compression  percentage  for
       each compacted file while uncompact and ccat will print out the name of
       each file as they're uncompacted.

RESTRICTION
       The last segment of the filename must be short enough  to  allow	 space
       for the appended '.C'.

FILES
       *.C	 compacted file created by compact, removed by uncompact

SEE ALSO
       Gallager,  Robert  G.,  `Variations  on	a  Theme of Huffman', I.E.E.E.
       Transactions on Information Theory, vol. IT-24, no. 6,  November	 1978,
       pp. 668 - 674.

AUTHOR
       Colin L. Mc Master

4th Berkeley Distribution	 April 2, 1994			    COMPACT(1)
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