66 lines
3.1 KiB
Text
66 lines
3.1 KiB
Text
Description
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Clzip is a lossless data compressor based on the LZMA algorithm, with
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very safe integrity checking and a user interface similar to the one of
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gzip or bzip2. Clzip decompresses almost as fast as gzip and compresses
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better than bzip2, which makes it well suited for software distribution
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and data archiving.
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Clzip replaces every file given in the command line with a compressed
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version of itself, with the name "original_name.lz". Each compressed
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file has the same modification date, permissions, and, when possible,
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ownership as the corresponding original, so that these properties can be
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correctly restored at decompression time. Clzip is able to read from some
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types of non regular files if the "--stdout" option is specified.
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If no file names are specified, clzip compresses (or decompresses) from
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standard input to standard output. In this case, clzip will decline to
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write compressed output to a terminal, as this would be entirely
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incomprehensible and therefore pointless.
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Clzip will correctly decompress a file which is the concatenation of two
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or more compressed files. The result is the concatenation of the
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corresponding uncompressed files. Integrity testing of concatenated
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compressed files is also supported.
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Clzip can produce multimember files and safely recover, with lziprecover,
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the undamaged members in case of file damage. Clzip can also split the
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compressed output in volumes of a given size, even when reading from
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standard input. This allows the direct creation of multivolume
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compressed tar archives.
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Clzip will automatically use the smallest possible dictionary size
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without exceeding the given limit. It is important to appreciate that
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the decompression memory requirement is affected at compression time by
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the choice of dictionary size limit.
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As a self-check for your protection, clzip stores in the member trailer
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the 32-bit CRC of the original data and the size of the original data,
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to make sure that the decompressed version of the data is identical to
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the original. This guards against corruption of the compressed data, and
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against undetected bugs in clzip (hopefully very unlikely). The chances
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of data corruption going undetected are microscopic, less than one
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chance in 4000 million for each member processed. Be aware, though, that
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the check occurs upon decompression, so it can only tell you that
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something is wrong. It can't help you recover the original uncompressed
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data.
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Clzip implements a simplified version of the LZMA (Lempel-Ziv-Markov
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chain-Algorithm) algorithm. The original LZMA algorithm was designed by
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Igor Pavlov.
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The high compression of LZMA comes from combining two basic, well-proven
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compression ideas: sliding dictionaries (LZ77/78) and markov models (the
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thing used by every compression algorithm that uses a range encoder or
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similar order-0 entropy coder as its last stage) with segregation of
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contexts according to what the bits are used for.
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Copyright (C) 2010 Antonio Diaz Diaz.
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This file is free documentation: you have unlimited permission to copy,
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distribute and modify it.
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The file Makefile.in is a data file used by configure to produce the
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Makefile. It has the same copyright owner and permissions that this
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file.
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