Return to compact.0 CVS log

Up to [CSRG BSD Unix] / 43BSDTahoe / old / compact

Annotation of 43BSDTahoe/old/compact/compact.0, revision 1.1.1.1

1.1       root        1: 
                      2: 
                      3: 
                      4: COMPACT(1)         UNIX Programmer's Manual           COMPACT(1)
                      5: 
                      6: 
                      7: 
                      8: NAME
                      9:      compact, uncompact, ccat - compress and uncompress files,
                     10:      and cat them
                     11: 
                     12: SYNOPSIS
                     13:      compact [ -v ] [ name ... ]
                     14:      uncompact [ -v ] [ name ...  ]
                     15:      ccat [ -v ] [ file ... ]
                     16: 
                     17: DESCRIPTION
                     18:      _C_o_m_p_a_c_t compresses the named files using an adaptive Huffman
                     19:      code.  If no file names are given, the standard input is
                     20:      compacted to the standard output. _C_o_m_p_a_c_t operates as an
                     21:      on-line algorithm.  Each time a byte is read, it is encoded
                     22:      immediately according to the current prefix code. This code
                     23:      is an optimal Huffman code for the set of frequencies seen
                     24:      so far.  It is unnecessary to prepend a decoding tree to the
                     25:      compressed file since the encoder and the decoder start in
                     26:      the same state and stay synchronized.  Furthermore, _c_o_m_p_a_c_t
                     27:      and _u_n_c_o_m_p_a_c_t can operate as filters.  In particular,
                     28: 
                     29:          ... | compact | uncompact | ...
                     30: 
                     31:      operates as a (very slow) no-op.
                     32: 
                     33:      When an argument _f_i_l_e is given, it is compacted and the
                     34:      resulting file is placed in _f_i_l_e._C; _f_i_l_e is unlinked.  The
                     35:      first two bytes of the compacted file code the fact that the
                     36:      file is compacted.  This code is used to prohibit recompac-
                     37:      tion.
                     38: 
                     39:      The amount of compression to be expected depends on the type
                     40:      of file being compressed. Typical values of compression
                     41:      are: Text (38%), Pascal Source (43%), C Source (36%) and
                     42:      Binary (19%).  These values are the percentages of file
                     43:      bytes reduced.
                     44: 
                     45:      _U_n_c_o_m_p_a_c_t restores the original file from a file compressed
                     46:      by _c_o_m_p_a_c_t. If no file names are given, the standard input
                     47:      is uncompacted to the standard output.
                     48: 
                     49:      _C_c_a_t cats the original file from a file compressed by _c_o_m_-
                     50:      _p_a_c_t, without uncompressing the file (it is just a shell
                     51:      script which directs the uncompacted output to the standard
                     52:      output).
                     53: 
                     54:      _C_o_m_p_a_c_t, _u_n_c_o_m_p_a_c_t, and _c_c_a_t normally do their work
                     55:      silently. If a -v flag is supplied, _c_o_m_p_a_c_t will report the
                     56:      compression percentage for each compacted file while _u_n_c_o_m_-
                     57:      _p_a_c_t and _c_c_a_t will print out the name of each file as
                     58:      they're uncompacted.
                     59: 
                     60: 
                     61: 
                     62: 
                     63: Printed 12/6/87          April 29, 1985                         1
                     64: 
                     65: 
                     66: 
                     67: 
                     68: 
                     69: 
                     70: COMPACT(1)         UNIX Programmer's Manual           COMPACT(1)
                     71: 
                     72: 
                     73: 
                     74: RESTRICTION
                     75:      The last segment of the filename must be short enough to
                     76:      allow space for the appended '.C'.
                     77: 
                     78: FILES
                     79:      *.C       compacted file created by compact, removed by
                     80:      uncompact
                     81: 
                     82: SEE ALSO
                     83:      Gallager, Robert G., `Variations on a Theme of Huffman',
                     84:      _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,
                     85:      no. 6, November 1978, pp. 668 - 674.
                     86: 
                     87: AUTHOR
                     88:      Colin L. Mc Master
                     89: 
                     90: 
                     91: 
                     92: 
                     93: 
                     94: 
                     95: 
                     96: 
                     97: 
                     98: 
                     99: 
                    100: 
                    101: 
                    102: 
                    103: 
                    104: 
                    105: 
                    106: 
                    107: 
                    108: 
                    109: 
                    110: 
                    111: 
                    112: 
                    113: 
                    114: 
                    115: 
                    116: 
                    117: 
                    118: 
                    119: 
                    120: 
                    121: 
                    122: 
                    123: 
                    124: 
                    125: 
                    126: 
                    127: 
                    128: 
                    129: Printed 12/6/87          April 29, 1985                         2
                    130: 
                    131: 
                    132: 

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.