/[packages]/cauldron/bzip2/current/SOURCES/bzme.1
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Contents of /cauldron/bzip2/current/SOURCES/bzme.1

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Revision 241 - (show annotations) (download)
Fri Jan 7 12:50:50 2011 UTC (13 years, 3 months ago) by pterjan
File size: 4394 byte(s)
imported package bzip2
1 .PU
2 .TH bzip2 1
3 .SH NAME
4 bzme \- recompress gziped, ziped, ... files into bzip2
5
6 .SH SYNOPSIS
7 .ll +8
8 .B bzmz
9 .RB [ " \-fh " ]
10 [
11 .I "filenames \&..."
12 ]
13
14 .SH DESCRIPTION
15 .I bzme
16 recompresses files using the Burrows-Wheeler block sorting text compression
17 algorithm, and Huffman coding. Compression is generally considerably better
18 than that achieved by more conventional LZ77/LZ78-based compressors,
19 and approaches the performance of the PPM family of statistical compressors.
20
21 .I bzme
22 expects a list of file names to accompany the command-line flags.
23 Each file is replaced by a recompressed version of itself, with the name
24 as described in
25 .B "NEW NAMES"
26 section.
27
28 .I bzme
29 won't overwrite by default existing files. If you want this to happen, specify
30 the \-f flag.
31
32 .SH "NEW NAMES"
33 .I bzip2
34 attempts to guess the filename for the decompressed file
35 from that of the compressed file as follows:
36
37 filename.tgz becomes filename.tar.bz2
38 filename.tar.gz becomes filename.tar.bz2
39 filename.zip becomes filename.tar.bz2
40 filename.z becomes filename.bz2
41 filename.Z becomes filename.bz2
42 filename.gz becomes filename.bz2
43
44 If the file does not end in one of the recognised endings, \fI.tgz\fP,
45
46 or \fI.zip\fP,
47 .I bzme
48 complains that it cannot guess if the name of the recompressed file (ie it
49 doesn't detect the original name to be a file compressed in a known format)
50
51 .SH OPTIONS
52 .TP
53 .B \-f
54 Force overwrite of output files, even if
55 .I -k
56 is used. Normally,
57 .I bzip2
58 will not overwrite existing output files.
59
60 .TP
61 .B \-k
62 Keep (don't delete) input files during compression
63 or decompression.
64 .".TP
65 .".B \-q --quiet
66 ."Suppress non-essential warning messages. Messages pertaining to
67 ."I/O errors and other critical events will not be suppressed.
68 .".TP
69 .".B \-v --verbose
70 ."Verbose mode -- dysplay space gain (default)
71 .".TP
72 .".B \-L --license -V --version
73 ."Display the software version, license terms and conditions.
74
75 .SH SECURITY
76 .I bzme
77 will keep source file if there's an error while decompressing source file
78 or recompressing new file (or
79 .I -k
80 option is used of course).
81
82 .I bzme
83 won't overwite the target file, even if
84 .I -k
85 option is used, if the source file doesn't exists.
86
87 As a self-check for your protection,
88 .I bzip2
89 uses 32-bit CRCs to make sure that the decompressed version of a file is
90 identical to the original.
91 .BR
92 This offers a better protection against corruption
93 of the compressed data than offered by gzip.
94
95 .SH SPACE GAIN
96 Compression is only performed if the compressed file is smaller than the
97 original: the original file is only removed if the newly compressed file
98 is smaller, else the new recompressed file is deleted.
99
100 Text (aka non binary) files're quite nearly always better compressed
101 by bzip2 rather than gzip.
102
103 .SH MEMORY VS SPACE TRADEOFF
104 There're two things :
105 .TP
106 .B Consumed CPU time
107 The needed cpu time is reduced by decompressing only one time.
108 Files to recompress were compressed through compress or gzip, used to be
109 decompressed by gunzip -t in order to check that the original file was ok.
110 This resulted in passing two times the data in the decompression process
111 (one to check integrity, one to recompress).
112 temporary space usage will be zero since bzme will use a pipe
113 rather than a temporary file as it does in the early ages.
114 Source error're detected through bash PIPESTATUS feature.
115 .TP
116 .B Occupied space
117 While recompressing files, if they were compressed through compress or gzip,
118 temporary space usage will be zero since bzme will use a pipe
119 rather than a temporary file as it did in the early ages.
120 Source error're detected through bash PIPESTATUS feature.
121 Zip files're still fully decompressed on disk.
122
123 As for the recompressed file and original file, only the smallest file
124 is kept.
125
126 .SH RETURN VALUES
127 0 for a normal exit.
128 1 will be returned if an unknown option is passed.
129
130 .SH BUGS
131 Bash getopt (which is used to analyse options) isn't gnu style aware, ie cmd
132 opt1 file1 file2 opt2 will result in ignoring opt2 option.
133
134 Solaris/SunOs du doesn't supports gnu option, and thus, bzme won't
135 work on those OSes unless GNU fileutils got installed.
136 .BR
137 I had once a day patched bzme to use right options for solaris but i had
138 lost my changes.
139 .LP
140 So solaris remains unsupported.
141
142 .SH "SEE ALSO"
143 bzip2(1), bunzip2(1)
144
145 .SH AUTHOR
146 Thierry Vignaud <tvignaud@mandrakesoft.com>, 1999-2002

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