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| -rw-r--r-- | README | 65 |
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@@ -1,10 +1,10 @@ Description Clzip is a lossless data compressor with a user interface similar to the -one of gzip or bzip2. Clzip decompresses almost as fast as gzip and -compresses more than bzip2, which makes it well suited for software -distribution and data archiving. Clzip is a clean implementation of the -LZMA algorithm. +one of gzip or bzip2. Clzip decompresses almost as fast as gzip, +compresses most files more than bzip2, and is better than both from a +data recovery perspective. Clzip is a clean implementation of the LZMA +algorithm. Clzip uses the lzip file format; the files produced by clzip are fully compatible with lzip-1.4 or newer, and can be rescued with lziprecover. @@ -12,17 +12,23 @@ Clzip is in fact a C language version of lzip, intended for embedded devices or systems lacking a C++ compiler. The lzip file format is designed for long-term data archiving and -provides very safe integrity checking. The member trailer stores the -32-bit CRC of the original data, the size of the original data and the -size of the member. These values, together with the value remaining in -the range decoder and the end-of-stream marker, provide a 4 factor -integrity checking which guarantees that the decompressed version of the -data is identical to the original. This guards against corruption of the -compressed data, and against undetected bugs in clzip (hopefully very -unlikely). The chances of data corruption going undetected are -microscopic. Be aware, though, that the check occurs upon decompression, -so it can only tell you that something is wrong. It can't help you -recover the original uncompressed data. +provides very safe integrity checking. It is as simple as possible (but +not simpler), 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 lzip is copylefted, which guarantees that it will remain +free forever. + +The member trailer stores the 32-bit CRC of the original data, the size +of the original data and the size of the member. These values, together +with the value remaining in the range decoder and the end-of-stream +marker, provide a 4 factor integrity checking which guarantees that the +decompressed version of the data is identical to the original. This +guards against corruption of the compressed data, and against undetected +bugs in clzip (hopefully very unlikely). The chances of data corruption +going undetected are microscopic. Be aware, though, that the check +occurs upon decompression, so it can only tell you that something is +wrong. It can't help you recover the original uncompressed data. If you ever need to recover data from a damaged lzip file, try the lziprecover program. Lziprecover makes lzip files resistant to bit-flip @@ -31,15 +37,26 @@ recovery capabilities, including error-checked merging of damaged copies of a file. Clzip uses the same well-defined exit status values used by lzip and -bzip2, which makes it safer when used in pipes or scripts than -compressors returning ambiguous warning values, like gzip. +bzip2, which makes it safer than compressors returning ambiguous warning +values (like gzip) when it is used as a back end for tar or zutils. -Clzip replaces every file given in the command line with a compressed -version of itself, with the name "original_name.lz". Each compressed -file has the same modification date, permissions, and, when possible, -ownership as the corresponding original, so that these properties can be -correctly restored at decompression time. Clzip is able to read from some -types of non regular files if the "--stdout" option is specified. +When compressing, clzip replaces every file given in the command line +with a compressed version of itself, with the name "original_name.lz". +When decompressing, clzip attempts to guess the name for the decompressed +file from that of the compressed file as follows: + +filename.lz becomes filename +filename.tlz becomes filename.tar +anyothername becomes anyothername.out + +(De)compressing a file is much like copying or moving it; therefore clzip +preserves the access and modification dates, permissions, and, when +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). + +Clzip is able to read from some types of non regular files if the +"--stdout" option is specified. If no file names are specified, clzip compresses (or decompresses) from standard input to standard output. In this case, clzip will decline to @@ -81,7 +98,7 @@ range encoding), Igor Pavlov (for putting all the above together in LZMA), and Julian Seward (for bzip2's CLI). -Copyright (C) 2010, 2011, 2012, 2013 Antonio Diaz Diaz. +Copyright (C) 2010, 2011, 2012, 2013, 2014 Antonio Diaz Diaz. This file is free documentation: you have unlimited permission to copy, distribute and modify it. |