Return to compact.1 CVS log

Up to [Power 6/32 Unix Tahoe 4.2BSD] / cci / usr / src / man / man1

Annotation of cci/usr/src/man/man1/compact.1, revision 1.1.1.1

1.1       root        1: .TH COMPACT 1 "18 January 1983"
                      2: .UC 4
                      3: .SH NAME
                      4: compact, uncompact, ccat \- compress and uncompress files, and cat them
                      5: .SH SYNOPSIS
                      6: .B compact
                      7: [ name ... ]
                      8: .br
                      9: .B uncompact
                     10: [
                     11: name ...
                     12: ]
                     13: .br
                     14: .B ccat
                     15: [ file ... ]
                     16: .SH DESCRIPTION
                     17: .I Compact
                     18: compresses the named files using an adaptive Huffman code.  If no file
                     19: names are given, the standard input is compacted to the standard output.
                     20: .I Compact
                     21: operates as an on-line algorithm.  Each time a byte is read,
                     22: it is encoded immediately according to the current prefix code.
                     23: This code is an optimal Huffman code for the set of frequencies seen so far.
                     24: It is unnecessary to prepend a decoding tree to the compressed file
                     25: since the encoder and the decoder start in the same state and stay
                     26: synchronized.  Furthermore,
                     27: .I compact
                     28: and
                     29: .I uncompact
                     30: can operate as filters.  In particular,
                     31: .sp
                     32:        ... | compact | uncompact | ...
                     33: .br
                     34: .sp
                     35: operates as a (very slow) no-op.
                     36: .PP
                     37: When an argument
                     38: .I file
                     39: is given, it is compacted and the resulting file is placed in
                     40: .I file.C;
                     41: .I file
                     42: is unlinked.  The first two bytes of the compacted file code the
                     43: fact that the file is compacted.  This code is used to prohibit recompaction.
                     44: .PP
                     45: The amount of compression to be expected depends on the type of file being
                     46: compressed.  Typical values of compression are:
                     47: Text (38%), Pascal Source (43%), C Source (36%) and Binary (19%).
                     48: These values are the percentages of file bytes reduced.
                     49: .PP
                     50: .I Uncompact
                     51: restores the original file from a file compressed by
                     52: .I compact.
                     53: If no file names are given, the standard input is uncompacted to
                     54: the standard output.
                     55: .PP
                     56: .I Ccat
                     57: cats the original file from a file compressed by
                     58: .I compact,
                     59: without uncompressing the file.
                     60: .SH RESTRICTION
                     61: The last segment of the filename must contain fewer than thirteen characters
                     62: to allow space for the appended '.C'.
                     63: .SH FILES
                     64: .ta 1i
                     65: *.C    compacted file created by compact, removed by uncompact
                     66: .SH "SEE ALSO"
                     67: Gallager, Robert G., `Variations on a Theme of Huffman',
                     68: .I "I.E.E.E.  Transactions on Information Theory,"
                     69: vol. IT-24, no. 6, November 1978, pp. 668 - 674.
                     70: .SH AUTHOR
                     71: Colin L. Mc Master

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