lziprecover/README

See the file INSTALL for compilation and installation instructions.

Description

Lziprecover is a data recovery tool and decompressor for files in the lzip
compressed data format (.lz). Lziprecover also provides Forward Error
Correction (FEC) able to repair any kind of file.

Lziprecover can remove the damaged members from multimember files, for
example multimember tar.lz archives.

Lziprecover provides random access to the data in multimember files; it only
decompresses the members containing the desired data.

Lziprecover is not a replacement for regular backups, but a last line of
defense for the case where the backups are also damaged.

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.

Compression may be good for long-term archiving. For compressible data,
multiple compressed copies may provide redundancy in a more useful form and
may have a better chance of surviving intact than one uncompressed copy
using the same amount of storage space. This is especially true if the
format provides recovery capabilities like those of lziprecover, which is
able to find and combine the good parts of several damaged copies.

Lziprecover is able to recover or decompress files produced by any of the
compressors in the lzip family: lzip, plzip, minilzip/lzlib, clzip, and
pdlzip.

GNU ddrescue provides data recovery capabilities which nicely complement
those of lziprecover. If the cause of file corruption is a damaged medium,
the combination GNU ddrescue + lziprecover is the recommended option for
recovering data from damaged files.

If a file is too damaged for lziprecover to repair it, all the recoverable
data in all members of the file can be extracted with the command
'lziprecover -cd --ignore-errors file.lz > file'.

When recovering data, lziprecover takes as arguments the names of the
damaged files and writes zero or more recovered files depending on the
operation selected and whether the recovery succeeded or not. The damaged
files themselves are kept unchanged.

When decompressing or testing file integrity, lziprecover behaves like lzip
or lunzip.

The lziprecover package also includes unzcrash, a program written to test
robustness to decompression of corrupted data, inspired by unzcrash.c from
Julian Seward's bzip2. Type 'make unzcrash' in the lziprecover source
directory to build it. Then try 'unzcrash --help'.

Lziprecover uses Arg_parser for command-line argument parsing:
http://www.nongnu.org/arg-parser/arg_parser.html


Copyright (C) 2009-2025 Antonio Diaz Diaz.

This file is free documentation: you have unlimited permission to copy,
distribute, and modify it.

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