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[Lzip-bug] Tarlz 0.6 released
Antonio Diaz Diaz
[Lzip-bug] Tarlz 0.6 released
Sun, 21 Oct 2018 17:13:39 +0200
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I am pleased to announce the release of tarlz 0.6.
Tarlz is a small and simple implementation of the tar archiver. By
default tarlz creates, lists and extracts archives in a simplified posix
pax 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.
Of course, compressing each file (or each directory) individually is
less efficient than compressing the whole tar archive, but it has the
* 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.
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.
Because of this, tarlz protects the extended records with a CRC in a way
compatible with standard tar tools.
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:
| header | data | extended header | extended data | header | data | eof |
| member | member | member |
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 homepage is at http://www.nongnu.org/lzip/tarlz.html
An online manual for tarlz can be found at
The sources can be downloaded from
The sha256sum is:
Changes in version 0.6:
* The new option '-A, --concatenate', which appends tar.lz archives
to the end of a tar.lz archive, has been added.
* The option '--ignore-crc' has been replaced with '--missing-crc' to
improve backwards compatibility with the pax format. Missing CRCs are
now ignored by default and only reported as errors if '--missing-crc' is
* Tarlz now tests that uid, gid, mtime, devmajor and devminor are in
ustar range when adding members to an archive.
* The configure script now accepts appending options to CXXFLAGS
using the syntax 'CXXFLAGS+=OPTIONS'.
* 'make dist' now uses tarlz to create the source tarball.
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
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