Description Lziprecover is a data recovery tool and decompressor for files in the lzip compressed data format (.lz). Lziprecover is able to repair slightly damaged files (up to one single-byte error per member), produce a correct file by merging the good parts of two or more damaged copies, reproduce a missing (zeroed) sector using a reference file, extract data from damaged files, decompress files, and test integrity of files. 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 facilitates the management of metadata stored as trailing data in lzip files. Lziprecover is not a replacement for regular backups, but a last line of defense for the case where the backups are also damaged. 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. 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. If the cause of file corruption is a damaged medium, the combination GNU ddrescue + lziprecover is the recommended option for recovering data from damaged lzip 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 in one step 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. To give you an idea of its possibilities, when merging two copies, each of them with one damaged area affecting 1 percent of the copy, the probability of obtaining a correct file is about 98 percent. With three such copies the probability rises to 99.97 percent. For large files (a few MB) with small errors (one sector damaged per copy), the probability approaches 100 percent even with only two copies. (Supposing that the errors are randomly located inside each copy). 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'. Copyright (C) 2009-2023 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.