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Annotation of 43BSDTahoe/old/compact/compact.1, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1980 Regents of the University of California.
        !             2: .\" All rights reserved.  The Berkeley software License Agreement
        !             3: .\" specifies the terms and conditions for redistribution.
        !             4: .\"
        !             5: .\"    @(#)compact.1   6.1 (Berkeley) 4/29/85
        !             6: .\"
        !             7: .TH COMPACT 1 "April 29, 1985"
        !             8: .UC 4
        !             9: .SH NAME
        !            10: compact, uncompact, ccat \- compress and uncompress files, and cat them
        !            11: .SH SYNOPSIS
        !            12: .B compact
        !            13: [
        !            14: .B \-v
        !            15: ] [ name ... ]
        !            16: .br
        !            17: .B uncompact
        !            18: [
        !            19: .B \-v
        !            20: ] [ name ...  ]
        !            21: .br
        !            22: .B ccat
        !            23: [
        !            24: .B \-v
        !            25: ] [ file ... ]
        !            26: .SH DESCRIPTION
        !            27: .I Compact
        !            28: compresses the named files using an adaptive Huffman code.  If no file
        !            29: names are given, the standard input is compacted to the standard output.
        !            30: .I Compact
        !            31: operates as an on-line algorithm.  Each time a byte is read,
        !            32: it is encoded immediately according to the current prefix code.
        !            33: This code is an optimal Huffman code for the set of frequencies seen so far.
        !            34: It is unnecessary to prepend a decoding tree to the compressed file
        !            35: since the encoder and the decoder start in the same state and stay
        !            36: synchronized.  Furthermore,
        !            37: .I compact
        !            38: and
        !            39: .I uncompact
        !            40: can operate as filters.  In particular,
        !            41: .sp
        !            42:        ... | compact | uncompact | ...
        !            43: .br
        !            44: .sp
        !            45: operates as a (very slow) no-op.
        !            46: .PP
        !            47: When an argument
        !            48: .I file
        !            49: is given, it is compacted and the resulting file is placed in
        !            50: .I file.C;
        !            51: .I file
        !            52: is unlinked.  The first two bytes of the compacted file code the
        !            53: fact that the file is compacted.  This code is used to prohibit recompaction.
        !            54: .PP
        !            55: The amount of compression to be expected depends on the type of file being
        !            56: compressed.  Typical values of compression are:
        !            57: Text (38%), Pascal Source (43%), C Source (36%) and Binary (19%).
        !            58: These values are the percentages of file bytes reduced.
        !            59: .PP
        !            60: .I Uncompact
        !            61: restores the original file from a file compressed by
        !            62: .I compact.
        !            63: If no file names are given, the standard input is uncompacted to
        !            64: the standard output.
        !            65: .PP
        !            66: .I Ccat
        !            67: cats the original file from a file compressed by
        !            68: .I compact,
        !            69: without uncompressing the file (it is just a shell script which
        !            70: directs the uncompacted output to the standard output).
        !            71: .PP
        !            72: .IR Compact ,
        !            73: .IR uncompact ,
        !            74: and
        !            75: .I ccat
        !            76: normally do their work silently.  If a
        !            77: .B \-v
        !            78: flag is supplied, 
        !            79: .I compact
        !            80: will report the compression percentage for each compacted
        !            81: file while 
        !            82: .I uncompact
        !            83: and
        !            84: .I ccat
        !            85: will print out the name of each file as they're uncompacted.
        !            86: .SH RESTRICTION
        !            87: The last segment of the filename must be short enough
        !            88: to allow space for the appended '.C'.
        !            89: .SH FILES
        !            90: .ta 1i
        !            91: *.C    compacted file created by compact, removed by uncompact
        !            92: .SH "SEE ALSO"
        !            93: Gallager, Robert G., `Variations on a Theme of Huffman',
        !            94: .I "I.E.E.E.  Transactions on Information Theory,"
        !            95: vol. IT-24, no. 6, November 1978, pp. 668 - 674.
        !            96: .SH AUTHOR
        !            97: Colin L. Mc Master

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