This is plzip.info, produced by makeinfo version 4.13 from plzip.texinfo. INFO-DIR-SECTION Data Compression START-INFO-DIR-ENTRY * Plzip: (plzip). Parallel version of the lzip data compressor END-INFO-DIR-ENTRY  File: plzip.info, Node: Top, Next: Introduction, Up: (dir) Plzip Manual ************ This manual is for Plzip (version 0.2, 17 January 2010). * Menu: * Introduction:: Purpose and features of plzip * Invoking Plzip:: Command line interface * File Format:: Detailed format of the compressed file * Problems:: Reporting bugs * Concept Index:: Index of concepts Copyright (C) 2009, 2010 Antonio Diaz Diaz. This manual is free documentation: you have unlimited permission to copy, distribute and modify it.  File: plzip.info, Node: Introduction, Next: Invoking Plzip, Prev: Top, Up: Top 1 Introduction ************** Plzip is a parallel version of the lzip data compressor. Currently only compression is performed in parallel. Parallel decompression is planned to be implemented later. Lzip is a lossless data compressor based on the LZMA algorithm, with very safe integrity checking and a user interface similar to the one of gzip or bzip2. Lzip decompresses almost as fast as gzip and compresses better than bzip2, which makes it well suited for software distribution and data archiving. 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. 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 uncompressed files. Integrity testing of concatenated compressed files is also supported. 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 As a self-check for your protection, plzip stores in the member trailer the 32-bit CRC of the original data and the size of the original data, to make sure 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 plzip (hopefully very unlikely). The chances of data corruption going undetected are microscopic, less than one chance in 4000 million for each member processed. 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. Return values: 0 for a normal exit, 1 for environmental problems (file not found, invalid flags, I/O errors, etc), 2 to indicate a corrupt or invalid input file, 3 for an internal consistency error (eg, bug) which caused plzip to panic.  File: plzip.info, Node: Invoking Plzip, Next: File Format, Prev: Introduction, Up: Top 2 Invoking Plzip **************** The format for running plzip is: plzip [OPTIONS] [FILES] Plzip supports the following options: `--help' `-h' Print an informative help message describing the options and exit. `--version' `-V' Print the version number of plzip on the standard output and exit. `--stdout' `-c' Compress or decompress to standard output. Needed when reading from a named pipe (fifo) or from a device. `--decompress' `-d' Decompress. `--force' `-f' Force overwrite of output file. `--keep' `-k' Keep (don't delete) input files during compression or decompression. `--match-length=LENGTH' `-m LENGTH' Set the match length limit in bytes. Valid values range from 5 to 273. Larger values usually give better compression ratios but longer compression times. `--output=FILE' `-o FILE' When reading from standard input and `--stdout' has not been specified, use `FILE' as the virtual name of the uncompressed file. This produces a file named `FILE' when decompressing, and a file named `FILE.lz' when compressing. `--quiet' `-q' Quiet operation. Suppress all messages. `--dictionary-size=SIZE' `-s SIZE' Set the dictionary size limit in bytes. Valid values range from 4KiB to 512MiB. Note that dictionary sizes are quantized. If the specified size does not match one of the valid sizes, it will be rounded upwards. `--test' `-t' Check integrity of the specified file(s), but don't decompress them. This really performs a trial decompression and throws away the result. Use `-tvv' or `-tvvv' to see information about the file. `--verbose' `-v' Verbose mode. Show the compression ratio for each file processed. Further -v's increase the verbosity level. `-1 .. -9' Set the compression parameters (dictionary size and match length limit) as shown in the table below. Note that `-9' can be much slower than `-1'. These options have no effect when decompressing. Level Dictionary size Match length limit -1 1MiB 10 bytes -2 1MiB 12 bytes -3 1MiB 17 bytes -4 2MiB 26 bytes -5 4MiB 44 bytes -6 8MiB 80 bytes -7 16MiB 108 bytes -8 16MiB 163 bytes -9 32MiB 273 bytes `--fast' `--best' Aliases for GNU gzip compatibility. Numbers given as arguments to options may be followed by a multiplier and an optional `B' for "byte". Table of SI and binary prefixes (unit multipliers): Prefix Value | Prefix Value k kilobyte (10^3 = 1000) | Ki kibibyte (2^10 = 1024) M megabyte (10^6) | Mi mebibyte (2^20) G gigabyte (10^9) | Gi gibibyte (2^30) T terabyte (10^12) | Ti tebibyte (2^40) P petabyte (10^15) | Pi pebibyte (2^50) E exabyte (10^18) | Ei exbibyte (2^60) Z zettabyte (10^21) | Zi zebibyte (2^70) Y yottabyte (10^24) | Yi yobibyte (2^80)  File: plzip.info, Node: File Format, Next: Problems, Prev: Invoking Plzip, Up: Top 3 File Format ************* In the diagram below, a box like this: +---+ | | <-- the vertical bars might be missing +---+ represents one byte; a box like this: +==============+ | | +==============+ represents a variable number of bytes. A lzip file consists of a series of "members" (compressed data sets). The members simply appear one after another in the file, with no additional information before, between, or after them. Each member has the following structure: +--+--+--+--+----+----+=============+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ID string | VN | DS | Lzma stream | CRC32 | Data size | Member size | +--+--+--+--+----+----+=============+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ All multibyte values are stored in little endian order. `ID string' A four byte string, identifying the member type, with the value "LZIP". `VN (version number, 1 byte)' Just in case something needs to be modified in the future. Valid values are 0 and 1. Version 0 files have only one member and lack `Member size'. `DS (coded dictionary size, 1 byte)' Bits 4-0 contain the base 2 logarithm of the base dictionary size. Bits 7-5 contain the number of "wedges" to substract from the base dictionary size to obtain the dictionary size. The size of a wedge is (base dictionary size / 16). Valid values for dictionary size range from 4KiB to 512MiB. `Lzma stream' The lzma stream, finished by an end of stream marker. Uses default values for encoder properties. `CRC32 (4 bytes)' CRC of the uncompressed original data. `Data size (8 bytes)' Size of the uncompressed original data. `Member size (8 bytes)' Total size of the member, including header and trailer. This facilitates safe recovery of undamaged members from multimember files.  File: plzip.info, Node: Problems, Next: Concept Index, Prev: File Format, Up: Top 4 Reporting Bugs **************** There are probably bugs in plzip. There are certainly errors and omissions in this manual. If you report them, they will get fixed. If you don't, no one will ever know about them and they will remain unfixed for all eternity, if not longer. If you find a bug in plzip, please send electronic mail to . Include the version number, which you can find by running `plzip --version'.  File: plzip.info, Node: Concept Index, Prev: Problems, Up: Top Concept Index ************* [index] * Menu: * bugs: Problems. (line 6) * file format: File Format. (line 6) * getting help: Problems. (line 6) * introduction: Introduction. (line 6) * invoking: Invoking Plzip. (line 6) * options: Invoking Plzip. (line 6) * usage: Invoking Plzip. (line 6) * version: Invoking Plzip. (line 6)  Tag Table: Node: Top227 Node: Introduction750 Node: Invoking Plzip3402 Node: File Format6747 Node: Problems8703 Node: Concept Index9232  End Tag Table