lunzip/README

Description

Lunzip is a decompressor for lzip files. It is written in C and its
small size makes it well suited for embedded devices or software
installers that need to decompress files but do not need compression
capabilities. Lunzip is fully compatible with lzip-1.4 or newer.

The lzip file format is designed for long-term data archiving. It is
clean, provides very safe 4 factor integrity checking, and is backed by
the recovery capabilities of lziprecover.

Lunzip uses the same well-defined exit status values used by lzip and
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 "--buffer-size" option and lunzip will use the decompressed
file as dictionary for distances beyond the buffer size. Of course, the
smaller the output buffer size used in relation to 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.

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
the "--buffer-size" option 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, 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).

Lunzip is able to read from some types of non regular files if the
"--stdout" option is specified.

If no file names are specified, lunzip decompresses from standard input
to standard output. In this case, lunzip will decline to read compressed
input from a terminal.

Lunzip 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.

The ideas embodied in lunzip are due to (at least) the following people:
Abraham Lempel and Jacob Ziv (for the LZ algorithm), Andrey 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).


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.

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.