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Diffstat (limited to 'README')
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@@ -1,8 +1,15 @@ Description -Plzip is a massively parallel (multi-threaded) lossless data compressor -based on the lzlib compression library, with a user interface similar to -the one of lzip, bzip2 or gzip. +Plzip is a massively parallel (multi-threaded) implementation of lzip, fully +compatible with lzip 1.4 or newer. Plzip uses the lzlib compression library. + +Lzip is a lossless data compressor with a user interface similar to the +one of gzip or bzip2. Lzip can compress about as fast as gzip (lzip -0) +or compress most files more than bzip2 (lzip -9). Decompression speed is +intermediate between gzip and bzip2. Lzip is better than gzip and bzip2 +from a data recovery perspective. Lzip has been designed, written and +tested with great care to replace gzip and bzip2 as the standard +general-purpose compressed format for unix-like systems. Plzip can compress/decompress large files on multiprocessor machines much faster than lzip, at the cost of a slightly reduced compression @@ -21,25 +28,21 @@ be decompressed faster than using lzip (unless the '-b' option was used) because lzip usually produces single-member files, which can't be decompressed in parallel. -Plzip uses the lzip file format; the files produced by plzip are fully -compatible with lzip-1.4 or newer, and can be rescued with lziprecover. - -The lzip file format is designed for data sharing and long-term -archiving, taking into account both data integrity and decoder -availability: +The lzip file format is designed for data sharing and long-term archiving, +taking into account both data integrity and decoder availability: * The lzip format provides very safe integrity checking and some data - recovery means. The lziprecover program can repair bit-flip errors + recovery means. The lziprecover program can repair bit flip errors (one of the most common forms of data corruption) in lzip files, and provides data recovery capabilities, including error-checked merging of damaged copies of a file. * The lzip format is as simple as possible (but not simpler). The - lzip manual provides the source code of a simple decompressor along - with a detailed explanation of how it works, so that with the only - help of the lzip manual it would be possible for a digital - archaeologist to extract the data from a lzip file long after - quantum computers eventually render LZMA obsolete. + lzip manual provides the source code of a simple decompressor + along with a detailed explanation of how it works, so that with + the only help of the lzip manual it would be possible for a + digital archaeologist to extract the data from a lzip file long + after quantum computers eventually render LZMA obsolete. * Additionally the lzip reference implementation is copylefted, which guarantees that it will remain free forever. @@ -49,15 +52,14 @@ repair the nearer it is from the beginning of the file. Therefore, with the help of lziprecover, losing an entire archive just because of a corrupt byte near the beginning is a thing of the past. -Plzip uses the same well-defined exit status values used by lzip and -bzip2, which makes it safer than compressors returning ambiguous warning -values (like gzip) when it is used as a back end for other programs like -tar or zutils. +Plzip uses the same well-defined exit status values used by lzip, which +makes it safer than compressors returning ambiguous warning values (like +gzip) when it is used as a back end for other programs like tar or zutils. -Plzip will automatically use the smallest possible dictionary size for -each file without exceeding the given limit. Keep in mind that the -decompression memory requirement is affected at compression time by the -choice of dictionary size limit. +Plzip will automatically use for each file the largest dictionary size +that does not exceed neither the file size nor the limit given. Keep in +mind that the decompression memory requirement is affected at +compression time by the choice of dictionary size limit. When compressing, plzip replaces every file given in the command line with a compressed version of itself, with the name "original_name.lz". @@ -70,25 +72,29 @@ anyothername becomes anyothername.out (De)compressing a file is much like copying or moving it; therefore plzip preserves the access and modification dates, permissions, and, when -possible, ownership of the file just as "cp -p" does. (If the user ID or +possible, ownership of the file just as 'cp -p' does. (If the user ID or the group ID can't be duplicated, the file permission bits S_ISUID and S_ISGID are cleared). Plzip is able to read from some types of non regular files if the -"--stdout" option is specified. +'--stdout' option is specified. If no file names are specified, plzip compresses (or decompresses) from standard input to standard output. In this case, plzip will decline to write compressed output to a terminal, as this would be entirely incomprehensible and therefore pointless. -Plzip will correctly decompress a file which is the concatenation of two -or more compressed files. The result is the concatenation of the -corresponding decompressed files. Integrity testing of concatenated -compressed files is also supported. +Plzip will correctly decompress a file which is the concatenation of two or +more compressed files. The result is the concatenation of the corresponding +decompressed files. Integrity testing of concatenated compressed files is +also supported. + +LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may never +have been compressed. Decompressed is used to refer to data which have +undergone the process of decompression. -Copyright (C) 2009-2018 Antonio Diaz Diaz. +Copyright (C) 2009-2019 Antonio Diaz Diaz. This file is free documentation: you have unlimited permission to copy, distribute and modify it. |