


      CCCCOOOOMMMMPPPPAAAACCCCTTTT((((1111))))                  ((((bbbbssssdddd 4444....2222))))                  CCCCOOOOMMMMPPPPAAAACCCCTTTT((((1111))))



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

      SSSSYYYYNNNNTTTTAAAAXXXX
           ccccoooommmmppppaaaacccctttt [ name ... ]
           uuuunnnnccccoooommmmppppaaaacccctttt [ name ...  ]
           ccccccccaaaatttt [ file ... ]

      DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
           _C_o_m_p_a_c_t compresses the named files using an adaptive Huffman
           code.  If no file names are given, the standard input is
           compacted to the standard output.  _C_o_m_p_a_c_t 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
           compressed file since the encoder and the decoder start in
           the same state and stay synchronized.  Furthermore, _c_o_m_p_a_c_t
           and _u_n_c_o_m_p_a_c_t can operate as filters.  In particular,

                ... | compact | uncompact | ...

           operates as a (very slow) no-op.

           When an argument _f_i_l_e is given, it is compacted and the
           resulting file is placed in _f_i_l_e._C; _f_i_l_e is unlinked.  The
           first two bytes of the compacted 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%), Pascal Source (43%), C Source (36%) and
           Binary (19%).  These values are the percentages of file
           bytes reduced.

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

           _C_c_a_t cats the original file from a file compressed by
           _c_o_m_p_a_c_t, without uncompressing the file.

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

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




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      CCCCOOOOMMMMPPPPAAAACCCCTTTT((((1111))))                  ((((bbbbssssdddd 4444....2222))))                  CCCCOOOOMMMMPPPPAAAACCCCTTTT((((1111))))



      SSSSEEEEEEEE AAAALLLLSSSSOOOO
           Gallager, Robert G., `Variations on a Theme of Huffman',
           _I._E._E._E.  _T_r_a_n_s_a_c_t_i_o_n_s _o_n _I_n_f_o_r_m_a_t_i_o_n _T_h_e_o_r_y, vol. IT-24,
           no. 6, November 1978, pp. 668 - 674.

           pack(1)

















































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