version 1.23 - Sergey Poznyakoff, 2010-03-10

* Record size autodetection

When listing or extracting archives, the actual record size is
reported only if the archive is read from a device (as opposed
to regular files and pipes).

* Seekable archives

When a read-only operation (e.g. --list or --extract) is requested
on a regular file, tar attemtps to speed up accesses by using lseek.

* New command line option `--warning'

The `--warning' command line option allows to suppress or enable
particular warning messages during `tar' run.  It takes a single
argument (a `keyword'), identifying the class of warning messages
to affect.  If the argument is prefixed with `no-', such warning
messages are suppressed.  For example,

  tar --warning=no-alone-zero-block -x -f archive

suppresses the output of `A lone zero block' diagnostics, which is
normally issued if `archive' ends with a single block of zeros.

See Tar Manual, section 3.9 "Controlling Warning Messages", for a
detailed discussion.

* New command line option `--level'

The `--level=N' option sets the incremental dump level N.  It
is valid when used in conjunction with the -c and --listed-incremental
options.  So far the only meaningful value for N is 0.  The
`--level=0' option forces creating the level 0 dump, by truncating
the snapshot file if it exists.

* Files removed during incremental dumps

If a file or directory is removed while incremental dump is
in progress, tar exact actions depend on whether this file
was explicitly listed in the command line, or was found
during file system scan.

If the file was explicitly listed in the command line, tar
issues error message and exits with the code 2, meaning
fatal error.

Otherwise, if the file was found during the file system scan,
tar issues a warning, saying "File removed before we read it",
and sets exit code to 1, which means "some files differ".
If the --warning=no-file-removed option is given, no warning
is issued and exit code remains 0.

* Modification times of PAX extended headers.

Modification times in ustar header blocks of extended headers
are set to mtimes of the corresponding archive members.  This
can be overridden by the

  --pax-opion='exthdr.mtime=STRING'

command line option.  The STRING is either number of seconds since
the Epoch or a `Time reference' (see below).

Modification times in ustar header blocks of global extended
headers are set to the time when tar was invoked.

This can be overridden by the

  --pax-opion='globexthdr.mtime=STRING'

command line option.  The STRING is either number of seconds since
the Epoch or a `Time reference' (see below).

* Time references in --pax-option argument.

Any value from the --pax-option argument that is enclosed in a pair
of curly braces represents a time reference.  The string between the 
braces is understood either as a textual time representation, as described in
chapter 7, "Date input formats", of the Tar manual, or as a name of
an existing file, starting with `/' or `.'.  In the latter
case, it is replaced with the modification time of that file.

* Environment of --to-command script.

The environment passed to the --to-command script is extended with
the following variables:

   TAR_VERSION          GNU tar version number
   TAR_ARCHIVE          The name of the archive
   TAR_VOLUME           Ordinal number of the volume
   TAR_FORMAT           Format of the archive
   TAR_BLOCKING_FACTOR  Current blocking factor

* Bugfixes
** Fix handling of hard link targets by -c --transform.
** Fix hard links recognition with -c --remove-files.
** Fix restoring files from backup (debian bug #508199).
** Correctly restore modes and permissions on existing directories.
** The --remove-files option removes files only if they were
succesfully stored in the archive.
** Fix storing and listing of the volume labels in POSIX format.
** Improve algorithm for splitting long file names (ustar
format).
** Fix possible memory overflow in the rmt client code (CVE-2010-0624).