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diff --git a/doc/plzip.info b/doc/plzip.info index bf22e32..2070f4f 100644 --- a/doc/plzip.info +++ b/doc/plzip.info @@ -12,16 +12,16 @@ File: plzip.info, Node: Top, Next: Introduction, Up: (dir) Plzip Manual ************ -This manual is for Plzip (version 1.0-rc1, 8 March 2013). +This manual is for Plzip (version 1.0, 29 May 2013). * Menu: -* Introduction:: Purpose and features of plzip -* Program Design:: Internal structure of plzip -* Invoking Plzip:: Command line interface -* File Format:: Detailed format of the compressed file -* Problems:: Reporting bugs -* Concept Index:: Index of concepts +* Introduction:: Purpose and features of plzip +* Program Design:: Internal structure 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, 2011, 2012, 2013 Antonio Diaz Diaz. @@ -38,13 +38,19 @@ File: plzip.info, Node: Introduction, Next: Program Design, Prev: Top, Up: T Plzip is a massively parallel (multi-threaded), lossless data compressor based on the lzlib compression library, with very safe integrity checking and a user interface similar to the one of bzip2, gzip or 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. Plzip is intended for faster compression/decompression of big files on multiprocessor machines, which makes it specially well suited for distribution of big software files and large scale data archiving. On -files big enough, plzip can use hundreds of processors. +files big enough (several GB), plzip can use hundreds of processors. + + 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. + + 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. Plzip replaces every file given in the command line with a compressed version of itself, with the name "original_name.lz". Each compressed @@ -71,15 +77,16 @@ 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. +trailer 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 +very safe 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 plzip (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. WARNING! Even if plzip is bug-free, other causes may result in a corrupt compressed file (bugs in the system libraries, memory errors, @@ -88,11 +95,6 @@ give the `--keep' option to plzip and do not remove the original file until you verify the compressed file with a command like `plzip -cd file.lz | cmp file -'. - 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: Program Design, Next: Invoking Plzip, Prev: Introduction, Up: Top @@ -266,6 +268,12 @@ E exabyte (10^18) | Ei exbibyte (2^60) Z zettabyte (10^21) | Zi zebibyte (2^70) Y yottabyte (10^24) | Yi yobibyte (2^80) + + Exit status: 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: File Format, Next: Problems, Prev: Invoking Plzip, Up: Top @@ -323,7 +331,8 @@ additional information before, between, or after them. `Lzma stream' The lzma stream, finished by an end of stream marker. Uses default - values for encoder properties. + values for encoder properties. See the lzip manual for a full + description. `CRC32 (4 bytes)' CRC of the uncompressed original data. @@ -333,8 +342,9 @@ additional information before, between, or after them. `Member size (8 bytes)' Total size of the member, including header and trailer. This field - acts as a distributed index, and facilitates safe recovery of - undamaged members from multi-member files. + acts as a distributed index, allows the verification of stream + integrity, and facilitates safe recovery of undamaged members from + multi-member files. @@ -375,12 +385,12 @@ Concept Index Tag Table: Node: Top223 -Node: Introduction864 -Node: Program Design4030 -Node: Invoking Plzip5084 -Node: File Format10093 -Node: Problems12473 -Node: Concept Index13002 +Node: Introduction865 +Node: Program Design4113 +Node: Invoking Plzip5167 +Node: File Format10416 +Node: Problems12895 +Node: Concept Index13424 End Tag Table |