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Diffstat (limited to 'README')
| -rw-r--r-- | README | 38 |
1 files changed, 25 insertions, 13 deletions
@@ -6,12 +6,9 @@ the one of lzip, bzip2 or gzip. Plzip can compress/decompress large files on multiprocessor machines much faster than lzip, at the cost of a slightly reduced compression -ratio. On files large enough (several GB), plzip can use hundreds of -processors. On files of only a few MB it is better to use lzip. - -Plzip 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. +ratio. Note that the number of usable threads is limited by file size, +so on files larger than a few GB plzip can use hundreds of processors, +but on files of only a few MB plzip is no faster than lzip. 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. @@ -35,12 +32,27 @@ lziprecover program. Lziprecover makes lzip files resistant to bit-flip recovery capabilities, including error-checked merging of damaged copies of a file. -Plzip 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. Plzip is able to read from some -types of non regular files if the "--stdout" option is specified. +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 tar or zutils. + +When compressing, plzip replaces every file given in the command line +with a compressed version of itself, with the name "original_name.lz". +When decompressing, plzip 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 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 +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. If no file names are specified, plzip compresses (or decompresses) from standard input to standard output. In this case, plzip will decline to @@ -53,7 +65,7 @@ corresponding uncompressed files. Integrity testing of concatenated compressed files is also supported. -Copyright (C) 2009, 2010, 2011, 2012, 2013 Antonio Diaz Diaz. +Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014 Antonio Diaz Diaz. This file is free documentation: you have unlimited permission to copy, distribute and modify it. |