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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-14 12:54:40 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-14 12:54:40 +0000
commit47d9004eff8861813477ed571350f7cd83ea4fd4 (patch)
treef909edd49006917e1d3cdae838ca56f5fa7fc9ff /README
parentInitial commit. (diff)
downloadlunzip-upstream/1.14.tar.xz
lunzip-upstream/1.14.zip
Adding upstream version 1.14.upstream/1.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+Description
+
+Lunzip is a decompressor for the lzip format written in C. Its small size
+makes it well suited for embedded devices or software installers that need
+to decompress files but don't need compression capabilities. Lunzip is
+compatible with lzip 1.4 or newer.
+
+Lzip is a lossless data compressor with a user interface similar to the one
+of gzip or bzip2. Lzip uses a simplified form of the 'Lempel-Ziv-Markov
+chain-Algorithm' (LZMA) stream format to maximize interoperability. The
+maximum dictionary size is 512 MiB so that any lzip file can be decompressed
+on 32-bit machines. Lzip provides accurate and robust 3-factor integrity
+checking. 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.
+
+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 program lziprecover 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.
+
+ * Additionally the lzip reference implementation is copylefted, which
+ guarantees that it will remain free forever.
+
+A nice feature of the lzip format is that a corrupt byte is easier to 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.
+
+Lunzip uses the same well-defined exit status values used by bzip2, which
+makes it safer than decompressors returning ambiguous warning values (like
+gunzip) when it is used as a back end for other programs like tar or zutils.
+
+Lunzip provides a 'low memory' mode able to decompress any file using as
+little memory as 50 kB, irrespective of the dictionary size used to
+compress the file. To activate it, specify the size of the output buffer
+with the option '--buffer-size' and lunzip will use the decompressed
+file as dictionary for distances beyond the buffer size. Of course, the
+larger the difference between the buffer size and the dictionary size, the
+more accesses to disk are needed and the slower the decompression is.
+This 'low memory' mode only works when decompressing to a regular file
+and is intended for systems without enough memory (RAM + swap) to keep
+the whole dictionary at once. It has been tested on a laptop with a 486
+processor and 4 MiB of RAM.
+
+The option '--buffer-size' may help to decompress a file erroneously created
+with a dictionary size much larger than the uncompressed size. (Lzip adjusts
+the dictionary size to the uncompressed size, but third-party tools may not).
+
+The amount of memory required by lunzip to decompress a file is about 46 kB
+larger than the dictionary size used to compress that file, unless
+'--buffer-size' is specified.
+
+Lunzip 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
+
+Decompressing a file is much like copying or moving it. Therefore lunzip
+preserves the access and modification dates, permissions, and, if you have
+appropriate privileges, 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).
+
+Lunzip is able to read from some types of non-regular files if either the
+option '-c' or the option '-o' is specified.
+
+If no file names are specified, lunzip decompresses from standard input to
+standard output. In this case, lunzip refuses to read compressed input from
+a terminal, as this might leave the terminal in an abnormal state.
+
+Lunzip correctly decompresses 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.
+
+The ideas embodied in lunzip are due to (at least) the following people:
+Abraham Lempel and Jacob Ziv (for the LZ algorithm), Andrei Markov (for the
+definition of Markov chains), G.N.N. Martin (for the definition of range
+encoding), Igor Pavlov (for putting all the above together in LZMA), and
+Julian Seward (for bzip2's CLI).
+
+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) 2010-2024 Antonio Diaz Diaz.
+
+This file is free documentation: you have unlimited permission to copy,
+distribute, and modify it.
+
+The file Makefile.in is a data file used by configure to produce the Makefile.
+It has the same copyright owner and permissions that configure itself.