compact man page on Ultrix

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compact(1)							    compact(1)

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

       compact [name...]
       uncompact [name...]
       ccat [file...]

       The  command compresses the named files using an adaptive Huffman code.
       If no file names are given, the standard	 input	is  compacted  to  the
       standard	 output.   The command 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 fre‐
       quencies seen so far.  It is unnecessary to prepend a decoding tree  to
       the compressed file since the encoder and the decoder start in the same
       state and stay synchronized.  Furthermore, and 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.

       The  command restores the original file from a file compressed by If no
       file names are given, the standard input is uncompacted to the standard

       The  command  cats  the original file from a file compressed by without
       uncompressing the file.

       The command is present only for compatibility.  In general, the command
       runs faster and gives better compression.

       The  last  segment  of  the  file name must contain fewer than thirteen
       characters to allow space for the appended '.C'.

       compacted file created by compact, removed by uncompact

See Also


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