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[Lzip-bug] Tarlz 0.3 released

From: Antonio Diaz Diaz
Subject: [Lzip-bug] Tarlz 0.3 released
Date: Thu, 22 Mar 2018 13:06:43 +0100
User-agent: Mozilla/5.0 (X11; U; Linux i586; en-US; rv: Gecko/20110420 SeaMonkey/2.0.14

I am pleased to announce the release of tarlz 0.3.

Tarlz is a small and simple implementation of the tar archiver. By default tarlz creates, lists and extracts archives in the 'ustar' format compressed with lzip on a per file basis. Tarlz can append files to the end of such compressed archives.

Each tar member is compressed in its own lzip member, as well as the end-of-file blocks. This same method works for any tar format (gnu, ustar, posix) and is fully backward compatible with standard tar tools like GNU tar, which treat the resulting multimember tar.lz archive like any other tar.lz archive.

Tarlz can create tar archives with four levels of compression granularity; per file, per directory, appendable solid, and solid.

Tarlz is intended as a showcase project for the maintainers of real tar programs to evaluate the format and perhaps implement it in their tools.

The diagram below shows the correspondence between tar members (formed by a header plus optional data) in the tar archive and lzip members in the resulting multimember tar.lz archive:

| header | data | header | data | header | data |   eof  |

|     member    |     member    |     member    | member |

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 with plzip, 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, lziprecover can be used to recover at least part of the contents 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.

The homepage is at http://www.nongnu.org/lzip/tarlz.html

An online manual for tarlz can be found at http://www.nongnu.org/lzip/manual/tarlz_manual.html

The sources can be downloaded from http://download.savannah.gnu.org/releases/lzip/tarlz/tarlz-0.3.tar.lz

The sha256sum is:
a7fca2603f26ebc73026fae911a0cf648eb0807468b4a7d4bd56e970d528719c tarlz-0.3.tar.lz

Changes in version 0.3:

  * The project has been renamed to 'tarlz' from 'pmtar' (Poor Man's Tar).

  * The option '-C, --directory', has been added.

* Lzip compression of individual members at archive creation has been implemented.

* The option '-r, --append', has been added. It can append new members to a multimember compressed archive.

  * The options '--owner' and '--group' have been added.

* The options '--asolid', '--dsolid' and '--solid' have been added. They tell tarlz to create an (appendable) (per directory) solidly compressed archive.

  * Transparent decompression of the archive has been implemented.

* Skipping over damaged members (compressed or uncompressed) on archive list or extraction has been implemented.

  * Recursive extraction/listing of directories has been implemented.

  * Verbose extract/list output has been implemented.

  * An info manual has been added.

Please send bug reports and suggestions to address@hidden

Antonio Diaz, tarlz author and maintainer.

If you are distributing software in xz format, please consider using lzip instead. See http://www.nongnu.org/lzip/lzip_benchmark.html#xz1 and http://www.nongnu.org/lzip/xz_inadequate.html

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