version 1.20 - Sergey Poznyakoff, 2008-04-14

* New option --auto-compress (-a)

With --create, selects compression algorithm basing on the suffix
of the archive file name.

* New option --lzma

Selects LZMA compression algorithm

* New option --hard-dereference

During archive creation, dereferences hard links and stores the files
they refer to, instead of creating usual hard link members (type '1').

* New option --checkpoint-action

This action allows to specify an action to be executed upon hitting a
checkpoint.  Recognized actions are: dot, echo (the default),
echo=string, ttyout=string, exec=cmdline, and sleep=value.  Any number
of `--checkpoint-action' options can be specified, the actions will be
executed in order of their appearance in the command line.  See
chapter 3.8 "Checkpoints" for a complete description.

* New options --no-check-device, --check-device.

The `--no-check-device' option disables comparing device numbers during
preparatory stage of an incremental dump.  This allows to avoid
creating full dumps if the device numbers change (e.g. when using an
LVM snapshot).

The `--check-device' option enables comparing device numbers.  This is
the default.  This option is provided to undo the effect of the previous
`--no-check-device' option, e.g. if it was set in TAR_OPTIONS
environment variable.

* The --transform option.

Any number of `--transform' options can be given in the command line.
The specified transformations will be applied in turn.

The argument to `--transform' option can be a list of replace
expressions, separated by a semicolon (as in `sed').

Filename transformations are applied to symbolic link targets
during both creation and extraction.  Tar 1.19 used them only
during extraction.

For a detailed description, see chapter 6.7 "Modifying File and Member
Names". 

* Info (end-of-volume) scripts

The value of the blocking factor is made available to info and
checkpoint scripts via environment variable TAR_BLOCKING_FACTOR.

* Incremental archives

Improved (sped up) extracting from incremental archives.

* Bugfixes.
** Fix bug introduced in version 1.19: tar refused to update non-existing
archives.