Tarlz

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Introduction

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:

tar
+========+======+========+======+========+======+========+
| header | data | header | data | header | data |   eof  |
+========+======+========+======+========+======+========+

tar.lz
+===============+===============+===============+========+
|     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:

Documentation

The manual is available in the info system of the GNU Operating System. Use info to access the top level info page. Use info tarlz to access the tarlz section directly.

An online manual for tarlz can be found here.

Download

The latest released version of tarlz can be found at http://download.savannah.gnu.org/releases/lzip/tarlz/. You may also subscribe to lzip-bug and receive an email every time a new version is released.

How to get help

For general discussion of bugs in tarlz the mailing list lzip-bug@nongnu.org is the most appropriate forum. Please send messages as plain text. Please do not send messages encoded as HTML nor encoded as base64 MIME nor included as multiple formats. Please include a descriptive subject line. If all of the subject are "bug in tarlz" it is impossible to differentiate them.

An archive of the bug report mailing list is available at http://lists.gnu.org/mailman/listinfo/lzip-bug.

How to help

To contact the author, either to report a bug or to contribute fixes or improvements, send mail to lzip-bug@nongnu.org. Please send messages as plain text. If posting patches they should be in unified diff format against the latest version. They should include a text description.

See also the lzip project page at Savannah.

Licensing

Tarlz is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

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Copyright © 2018 Antonio Diaz Diaz
Lzip logo Copyright © 2013 Sonia Diaz Pacheco

You are free to copy, modify and distribute all or part of this article without limitation.

Updated: 2018-03-20