When performing operations, @command{tar} will skip files that match
@var{pattern}. @xref{exclude}.
+@opsummary{exclude-backups}
+@item --exclude-backups
+Exclude backup and lock files. @xref{exclude,, exclude-backups}.
+
@opsummary{exclude-from}
@item --exclude-from=@var{file}
@itemx -X @var{file}
Exclude from dump any directory containing a valid cache directory
tag file, but still dump the directory node and the tag file itself.
-@xref{exclude}.
+@xref{exclude,, exclude-caches}.
@opsummary{exclude-caches-under}
@item --exclude-caches-under
@item --exclude-tag=@var{file}
Exclude from dump any directory containing file named @var{file}, but
-dump the directory node and @var{file} itself. @xref{exclude}.
+dump the directory node and @var{file} itself. @xref{exclude,, exclude-tag}.
@opsummary{exclude-tag-under}
@item --exclude-tag-under=@var{file}
Exclude from dump the contents of any directory containing file
-named @var{file}, but dump the directory node itself. @xref{exclude}.
+named @var{file}, but dump the directory node itself. @xref{exclude,,
+exclude-tag-under}.
@opsummary{exclude-tag-all}
@item --exclude-tag-all=@var{file}
Exclude from dump any directory containing file named @var{file}.
-@xref{exclude}.
+@xref{exclude,,exclude-tag-all}.
@opsummary{exclude-vcs}
@item --exclude-vcs
Exclude from dump directories and files, that are internal for some
widely used version control systems.
-@xref{exclude}.
+@xref{exclude,,exclude-vcs}.
@opsummary{file}
@item --file=@var{archive}
With other operations, informs @command{tar} that the archive is in
incremental format. @xref{Incremental Dumps}.
+@opsummary{lzip}
+@item --lzip
+
+This option tells @command{tar} to read or write archives through
+@command{lzip}. @xref{gzip}.
+
@opsummary{lzma}
@item --lzma
@opsummary{pax-option}
@item --pax-option=@var{keyword-list}
-This option is meaningful only with @acronym{POSIX.1-2001} archives
-(@pxref{posix}). It modifies the way @command{tar} handles the
+This option enables creation of the archive in @acronym{POSIX.1-2001}
+format (@pxref{posix}) and modifies the way @command{tar} handles the
extended header keywords. @var{Keyword-list} is a comma-separated
list of keyword options. @xref{PAX keywords}, for a detailed
discussion.
@vrindex TAR_ATIME, to-command environment
@item TAR_ATIME
Time of last access. It is a decimal number, representing seconds
-since the epoch. If the archive provides times with nanosecond
+since the Epoch. If the archive provides times with nanosecond
precision, the nanoseconds are appended to the timestamp after a
decimal point.
GID of the file owner.
@end table
-In addition to these variables, @env{TAR_VERSION} contains the
+Additionally, the following variables contain information about
+tar mode and the archive being processed:
+
+@table @env
+@vrindex TAR_VERSION, to-command environment
+@item TAR_VERSION
@GNUTAR{} version number.
+@vrindex TAR_ARCHIVE, to-command environment
+@item TAR_ARCHIVE
+The name of the archive @command{tar} is processing.
+
+@vrindex TAR_BLOCKING_FACTOR, to-command environment
+@item TAR_BLOCKING_FACTOR
+Current blocking factor (@pxref{Blocking}.
+
+@vrindex TAR_VOLUME, to-command environment
+@item TAR_VOLUME
+Ordinal number of the volume @command{tar} is processing.
+
+@vrindex TAR_FORMAT, to-command environment
+@item TAR_FORMAT
+Format of the archive being processed. @xref{Formats}, for a complete
+list of archive format names.
+@end table
+
If @var{command} exits with a non-0 status, @command{tar} will print
an error message similar to the following:
However, empty lines are OK.
+@table @option
@cindex version control system, excluding files
@cindex VCS, excluding files
@cindex SCCS, excluding files
@cindex Arch, excluding files
@cindex Mercurial, excluding files
@cindex Darcs, excluding files
-@table @option
@opindex exclude-vcs
@item --exclude-vcs
Exclude files and directories used by following version control
systems: @samp{CVS}, @samp{RCS}, @samp{SCCS}, @samp{SVN}, @samp{Arch},
@samp{Bazaar}, @samp{Mercurial}, and @samp{Darcs}.
-@end table
As of version @value{VERSION}, the following files are excluded:
@item @file{_darcs}
@end itemize
+@opindex exclude-backups
+@item --exclude-backups
+Exclude backup and lock files. This option causes exclusion of files
+that match the following shell globbing patterns:
+
+@table @asis
+@item .#*
+@item *~
+@item #*#
+@end table
+
+@end table
+
@findex exclude-caches
When creating an archive, the @option{--exclude-caches} option family
causes @command{tar} to exclude all directories that contain a @dfn{cache
@cindex gzip
@cindex bzip2
+@cindex lzip
@cindex lzma
@cindex lzop
@cindex compress
@GNUTAR{} is able to create and read compressed archives. It supports
-@command{gzip}, @command{bzip2}, @command{lzma} and @command{lzop} compression
-programs. For backward compatibility, it also supports
-@command{compress} command, although we strongly recommend against
-using it, because it is by far less effective than other compression
-programs@footnote{It also had patent problems in the past.}.
+a wide variety of compression programs, namely: @command{gzip},
+@command{bzip2}, @command{lzip}, @command{lzma}, @command{lzop},
+@command{xz} and traditional @command{compress}. The latter is
+supported mostly for backward compatibility, and we recommend
+against using it, because it is by far less effective than the other
+compression programs@footnote{It also had patent problems in the past.}.
Creating a compressed archive is simple: you just specify a
@dfn{compression option} along with the usual archive creation
commands. The compression option is @option{-z} (@option{--gzip}) to
create a @command{gzip} compressed archive, @option{-j}
(@option{--bzip2}) to create a @command{bzip2} compressed archive,
+@option{--lzip} to create an @asis{lzip} compressed archive,
@option{-J} (@option{--xz}) to create an @asis{XZ} archive,
@option{--lzma} to create an @asis{LZMA} compressed
archive, @option{--lzop} to create an @asis{LSOP} archive, and
@item @samp{.tz2} @tab @command{bzip2}
@item @samp{.tbz2} @tab @command{bzip2}
@item @samp{.tbz} @tab @command{bzip2}
+@item @samp{.lz} @tab @command{lzip}
@item @samp{.lzma} @tab @command{lzma}
@item @samp{.tlz} @tab @command{lzma}
@item @samp{.lzo} @tab @command{lzop}
@itemx --bzip2
Filter the archive through @code{bzip2}. Otherwise like @option{--gzip}.
+@opindex lzip
+@item --lzip
+Filter the archive through @command{lzip}. Otherwise like @option{--gzip}.
+
@opindex lzma
@item --lzma
Filter the archive through @command{lzma}. Otherwise like @option{--gzip}.
%d/PaxHeaders.%p/%f
@end smallexample
+@item exthdr.mtime=@var{value}
+
+This keyword defines the value of the @samp{mtime} field that
+is written into the ustar header blocks for the extended headers.
+By default, the @samp{mtime} field is set to the modification time
+of the archive member described by that extended headers.
+
@item globexthdr.name=@var{string}
This keyword allows user control over the name that is written into
the ustar header blocks for global extended header records. The name
environment variable. If @var{TMPDIR} is not set, @command{tar}
uses @samp{/tmp}.
+@item exthdr.mtime=@var{value}
+
+This keyword defines the value of the @samp{mtime} field that
+is written into the ustar header blocks for the global extended headers.
+By default, the @samp{mtime} field is set to the time when
+@command{tar} was invoked.
+
@item @var{keyword}=@var{value}
When used with one of archive-creation commands, these keyword/value pairs
will be included at the beginning of the archive in a global extended
stored in the archive.
@end table
+In any of the forms described above, the @var{value} may be
+a string enclosed in curly braces. In that case, the string
+between the braces is understood either as a textual time
+representation, as described in @ref{Date input formats}, or a name of
+the existing file, starting with @samp{/} or @samp{.}. In the latter
+case, the modification time of that file is used.
+
+For example, to set all modification times to the current date, you
+use the following option:
+
+@smallexample
+--pax-option='mtime:=@{now@}'
+@end smallexample
+
+Note quoting of the option's argument.
+
+@cindex archives, binary equivalent
+@cindex binary equivalent archives, creating
+As another example, here is the option that ensures that any two
+archives created using it, will be binary equivalent if they have the
+same contents:
+
+@smallexample
+--pax-option=exthdr.name=%d/PaxHeaders/%f,atime:=0
+@end smallexample
+
@node Checksumming
@subsection Checksumming Problems
projects / chaz / tar / blobdiff