Description Tarlz is a combined implementation of the tar archiver and the lzip compressor. By default tarlz creates, lists and extracts archives in a simplified posix pax format compressed with lzip on a per file basis. Each tar member is compressed in its own lzip member, as well as the end-of-file blocks. This method adds an indexed lzip layer on top of the tar archive, making it possible to decode the archive safely in parallel. The resulting multimember tar.lz archive is fully backward compatible with standard tar tools like GNU tar, which treat it like any other tar.lz archive. Tarlz can append files to the end of such compressed archives. Tarlz can create tar archives with four levels of compression granularity; per file, per directory, appendable solid, and solid. Of course, compressing each file (or each directory) individually is less efficient than compressing the whole tar archive, but it has the following advantages: * The resulting multimember tar.lz archive can be decompressed in parallel, multiplying the decompression speed. * New members can be appended to the archive (by removing the EOF member) just like to an uncompressed tar archive. * It is a safe posix-style backup format. In case of corruption, tarlz can extract all the undamaged members from the tar.lz archive, skipping over the damaged members, just like the standard (uncompressed) tar. Moreover, the option '--keep-damaged' can be used to recover as much data as possible from each damaged member, and lziprecover can be used to recover some of the damaged members. * A multimember tar.lz archive is usually smaller than the corresponding solidly compressed tar.gz archive, except when individually compressing files smaller than about 32 KiB. Note that the posix pax format has a serious flaw. The metadata stored in pax extended records are not protected by any kind of check sequence. Corruption in a long filename may cause the extraction of the file in the wrong place without warning. Corruption in a large file size may cause the truncation of the file or the appending of garbage to the file, both followed by a spurious warning about a corrupt header far from the place of the undetected corruption. Metadata like filename and file size must be always protected in an archive format because of the adverse effects of undetected corruption in them, potentially much worse that undetected corruption in the data. Even more so in the case of pax because the amount of metadata it stores is potentially large, making undetected corruption more probable. Because of the above, tarlz protects the extended records with a CRC in a way compatible with standard tar tools. Tarlz does not understand other tar formats like gnu, oldgnu, star or v7. The diagram below shows the correspondence between each tar member (formed by one or two headers plus optional data) in the tar archive and each lzip member in the resulting multimember tar.lz archive: tar +========+======+=================+===============+========+======+========+ | header | data | extended header | extended data | header | data | EOF | +========+======+=================+===============+========+======+========+ tar.lz +===============+=================================================+========+ | member | member | member | +===============+=================================================+========+ Copyright (C) 2013-2019 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.