@smallbook
@c %**end of header
+@c Maintenance notes:
+@c 1. Pay attention to @FIXME{}s and @UNREVISED{}s
+@c 2. Before creating final variant:
+@c 1.1. Run `make check-options' to make sure all options are properly
+@c documented;
+@c 2.1. Run `make master-menu' (see comment before the master menu).
+
@include rendition.texi
@include value.texi
+@defcodeindex op
+
@c Put everything in one index (arbitrarily chosen to be the concept index).
@syncodeindex fn cp
@syncodeindex ky cp
@syncodeindex pg cp
@syncodeindex vr cp
-@defindex op
-
@copying
This manual is for @acronym{GNU} @command{tar} (version
document. The rest of the menu lists all the lower level nodes.
@end ifnottex
-@c The master menu, created with texinfo-master-menu, goes here.
-@c (However, getdate.texi's menu is interpolated by hand.)
+@c The master menu goes here.
+@c
+@c NOTE: To update it from within Emacs, make sure mastermenu.el is
+@c loaded and run texinfo-master-menu.
+@c To update it from the command line, run
+@c
+@c make master-menu
@menu
* Introduction::
* Changes::
* Configuring Help Summary::
* Genfile::
-* Snapshot Files::
-* Dumpdir::
+* Tar Internals::
* Free Software Needs Free Documentation::
* Copying This Manual::
* Index of Command Line Options::
* extracting archives::
* extracting files::
* extract dir::
+* extracting untrusted archives::
* failing commands::
Invoking @GNUTAR{}
The Three Option Styles
-* Mnemonic Options:: Mnemonic Option Style
+* Long Options:: Long Option Style
* Short Options:: Short Option Style
* Old Options:: Old Option Style
* Mixing:: Mixing Option Styles
Options Used by @option{--create}
+* override:: Overriding File Metadata.
* Ignore Failed Read::
Options Used by @option{--extract}
* Recursive Unlink::
* Data Modification Times::
* Setting Access Permissions::
+* Directory Modification Times and Permissions::
* Writing to Standard Output::
+* Writing to an External Program::
* remove files::
Coping with Scarce Resources
* problems with exclude::
+Wildcards Patterns and Matching
+
+* controlling pattern-matching::
+
Crossing File System Boundaries
* directory:: Changing Directory
* General date syntax:: Common rules.
* Calendar date items:: 19 Dec 1994.
* Time of day items:: 9:20pm.
-* Time zone items:: @sc{est}, @sc{pdt}, @sc{gmt}, ...
+* Time zone items:: @sc{est}, @sc{pdt}, @sc{gmt}.
* Day of week items:: Monday and others.
* Relative items in date strings:: next tuesday, 2 years ago.
* Pure numbers in date strings:: 19931219, 1440.
* Seconds since the Epoch:: @@1078100502.
+* Specifying time zone rules:: TZ="America/New_York", TZ="UTC0".
* Authors of get_date:: Bellovin, Eggert, Salz, Berets, et al.
Controlling the Archive Format
* Portability:: Making @command{tar} Archives More Portable
* Compression:: Using Less Space through Compression
* Attributes:: Handling File Attributes
-* Standard:: The Standard Format
-* Extensions:: @acronym{GNU} Extensions to the Archive Format
* cpio:: Comparison of @command{tar} and @command{cpio}
Making @command{tar} Archives More Portable
* Portable Names:: Portable Names
* dereference:: Symbolic Links
* old:: Old V7 Archives
+* ustar:: Ustar Archives
+* gnu:: GNU and old GNU format archives.
* posix:: @acronym{POSIX} archives
* Checksumming:: Checksumming Problems
* Large or Negative Values:: Large files, negative time stamps, etc.
+@GNUTAR{} and @acronym{POSIX} @command{tar}
+
+* PAX keywords:: Controlling Extended Header Keywords.
+
Using Less Space through Compression
* gzip:: Creating and Reading Compressed Archives
* Tape Files:: Tape Files
* Tarcat:: Concatenate Volumes into a Single Archive
-GNU tar internals and development
-* Genfile::
+Genfile
+
+* Generate Mode:: File Generation Mode.
+* Status Mode:: File Status Mode.
+* Exec Mode:: Synchronous Execution mode.
+
+Tar Internals
+
+* Standard:: Basic Tar Format
+* Extensions:: @acronym{GNU} Extensions to the Archive Format
+* Sparse Formats:: Storing Sparse Files
* Snapshot Files::
* Dumpdir::
+Storing Sparse Files
+
+* Old GNU Format::
+* PAX 0:: PAX Format, Versions 0.0 and 0.1
+* PAX 1:: PAX Format, Version 1.0
+
Copying This Manual
-* Free Software Needs Free Documentation::
* GNU Free Documentation License:: License for copying this manual
@end detailmenu
Fran@,{c}ois Pinard put version 1.11.8 of the manual together by
taking information from all these sources and merging them. Melissa
Weisshaus finally edited and redesigned the book to create version
-1.12. @FIXME{update version number as necessary; i'm being
-optimistic!} @FIXME{Someone [maybe karl berry? maybe bob chassell?
-maybe melissa? maybe julie sussman?] needs to properly index the
-thing.}
+1.12. The book for versions from 1.14 up to @value{VERSION} were edited
+by the current maintainer, Sergey Poznyakoff.
For version 1.12, Daniel Hagerty contributed a great deal of technical
consulting. In particular, he is the primary author of @ref{Backups}.
exist in @GNUTAR{} for compatibility with Unix
@command{tar}. In this book we present a full discussion of this way
of writing options and operations (@pxref{Old Options}), and we discuss
-the other two styles of writing options (@xref{Mnemonic Options}, and
+the other two styles of writing options (@xref{Long Options}, and
@pxref{Short Options}).
In the examples and in the text of this tutorial, we usually use the
@unnumberedsubsec The @option{--file} Option
@table @option
-@opindex file, tutorial
+@xopindex{file, tutorial}
@item --file=@var{archive-name}
@itemx -f @var{archive-name}
Specify the name of an archive file.
@unnumberedsubsec The @option{--verbose} Option
@table @option
-@opindex verbose, introduced
+@xopindex{verbose, introduced}
@item --verbose
@itemx -v
Show the files being worked on as @command{tar} is running.
clear, and we will give many examples both using and not using
@option{--verbose} to show the differences.
-Sometimes, a single instance of @option{--verbose} on the command line
-will show a full, @samp{ls} style listing of an archive or files,
-giving sizes, owners, and similar information. @FIXME{Describe the
-exact output format, e.g., how hard links are displayed.}
-Other times, @option{--verbose} will only show files or members that the particular
-operation is operating on at the time. In the latter case, you can
-use @option{--verbose} twice in a command to get a listing such as that
-in the former case. For example, instead of saying
+Each instance of @option{--verbose} on the command line increases the
+verbosity level by one, so if you need more details on the output,
+specify it twice.
+
+When reading archives (@option{--list}, @option{--extract},
+@option{--diff}), @command{tar} by default prints only the names of
+the members being extracted. Using @option{--verbose} will show a full,
+@command{ls} style member listing.
+
+In contrast, when writing archives (@option{--create}, @option{--append},
+@option{--update}), @command{tar} does not print file names by
+default. So, a single @option{--verbose} option shows the file names
+being added to the archive, while two @option{--verbose} options
+enable the full listing.
+
+For example, to create an archive in verbose mode:
@smallexample
-@kbd{tar -cvf afiles.tar apple angst aspic}
+$ @kbd{tar -cvf afiles.tar apple angst aspic}
+apple
+angst
+aspic
@end smallexample
@noindent
-above, you might say
+Creating the same archive with the verbosity level 2 could give:
@smallexample
-@kbd{tar -cvvf afiles.tar apple angst aspic}
+$ @kbd{tar -cvvf afiles.tar apple angst aspic}
+-rw-r--r-- gray/staff 62373 2006-06-09 12:06 apple
+-rw-r--r-- gray/staff 11481 2006-06-09 12:06 angst
+-rw-r--r-- gray/staff 23152 2006-06-09 12:06 aspic
@end smallexample
@noindent
Later in the tutorial, we will give examples using @w{@option{--verbose
--verbose}}.
+@anchor{verbose member listing}
+The full output consists of six fields:
+
+@itemize @bullet
+@item File type and permissions in symbolic form.
+These are displayed in the same format as the first column of
+@command{ls -l} output (@pxref{What information is listed,
+format=verbose, Verbose listing, fileutils, GNU file utilities}).
+
+@item Owner name and group separated by a slash character.
+If these data are not available (for example, when listing a @samp{v7} format
+archive), numeric ID values are printed instead.
+
+@item Size of the file, in bytes.
+
+@item File modification date in ISO 8601 format.
+
+@item File modification time.
+
+@item File name.
+If the name contains any special characters (white space, newlines,
+etc.) these are displayed in an unambiguous form using so called
+@dfn{quoting style}. For the detailed discussion of available styles
+and on how to use them, see @ref{quoting styles}.
+
+Depending on the file type, the name can be followed by some
+additional information, described in the following table:
+
+@table @samp
+@item -> @var{link-name}
+The file or archive member is a @dfn{symbolic link} and
+@var{link-name} is the name of file it links to.
+
+@item link to @var{link-name}
+The file or archive member is a @dfn{hard link} and @var{link-name} is
+the name of file it links to.
+
+@item --Long Link--
+The archive member is an old GNU format long link. You will normally
+not encounter this.
+
+@item --Long Name--
+The archive member is an old GNU format long name. You will normally
+not encounter this.
+
+@item --Volume Header--
+The archive member is a GNU @dfn{volume header} (@pxref{Tape Files}).
+
+@item --Continued at byte @var{n}--
+Encountered only at the beginning of a multy-volume archive
+(@pxref{Using Multiple Tapes}). This archive member is a continuation
+from the previous volume. The number @var{n} gives the offset where
+the original file was split.
+
+@item --Mangled file names--
+This archive member contains @dfn{mangled file names} declarations,
+a special member type that was used by early versions of @GNUTAR{}.
+You probably will never encounter this, unless you are reading a very
+old archive.
+
+@item unknown file type @var{c}
+An archive member of unknown type. @var{c} is the type character from
+the archive header. If you encounter such a message, it means that
+either your archive contains proprietary member types @GNUTAR{} is not
+able to handle, or the archive is corrupted.
+@end table
+
+@end itemize
+
+For example, here is an archive listing containing most of the special
+suffixes explained above:
+
+@smallexample
+@group
+V--------- 0/0 1536 2006-06-09 13:07 MyVolume--Volume Header--
+-rw-r--r-- gray/staff 456783 2006-06-09 12:06 aspic--Continued at
+byte 32456--
+-rw-r--r-- gray/staff 62373 2006-06-09 12:06 apple
+lrwxrwxrwx gray/staff 0 2006-06-09 13:01 angst -> apple
+-rw-r--r-- gray/staff 35793 2006-06-09 12:06 blues
+hrw-r--r-- gray/staff 0 2006-06-09 12:06 music link to blues
+@end group
+@end smallexample
+
+@smallexample
+@end smallexample
+
@node help tutorial
@unnumberedsubsec Getting Help: Using the @option{--help} Option
@node Creating the archive
@subsection Creating the Archive
-@opindex create, introduced
+@xopindex{create, introduced}
To place the files @file{blues}, @file{folk}, and @file{jazz} into an
archive named @file{collection.tar}, use the following command:
easiest to understand (and we encourage you to do the same when you use
@command{tar}, to avoid errors).
-Note that the part of the command which says,
-@w{@option{--file=collection.tar}} is considered to be @emph{one} argument.
+Note that the sequence
+@option{--file=@-collection.tar} is considered to be @emph{one} argument.
If you substituted any other string of characters for
@kbd{collection.tar}, then that string would become the name of the
archive file you create.
(@file{collection.tar}), and @option{--file} is the option which lets
you give it the name you chose. The files, @file{blues}, @file{folk},
and @file{jazz}, are now members of the archive, @file{collection.tar}
-(they are @dfn{file name arguments} to the @option{--create} operation).
-@FIXME-xref{to the discussion of file name args?}Now that they are
+(they are @dfn{file name arguments} to the @option{--create} operation.
+@xref{Choosing}, for the detailed discussion on these.) Now that they are
in the archive, they are called @emph{archive members}, not files.
(@pxref{Definitions,members}).
@node create verbose
@subsection Running @option{--create} with @option{--verbose}
-@opindex create, using with @option{--verbose}
-@opindex verbose, using with @option{--create}
+@xopindex{create, using with @option{--verbose}}
+@xopindex{verbose, using with @option{--create}}
If you include the @option{--verbose} (@option{-v}) option on the command line,
@command{tar} will list the files it is acting on as it is working. In
verbose mode, the @code{create} example above would appear as:
@opindex list
Frequently, you will find yourself wanting to determine exactly what a
-particular archive contains. You can use the @option{--list} (@option{-t}) operation
-to get the member names as they currently appear in the archive, as well
-as various attributes of the files at the time they were archived. For
-example, you can examine the archive @file{collection.tar} that you
-created in the last section with the command,
+particular archive contains. You can use the @option{--list}
+(@option{-t}) operation to get the member names as they currently
+appear in the archive, as well as various attributes of the files at
+the time they were archived. For example, you can examine the archive
+@file{collection.tar} that you created in the last section with the
+command,
@smallexample
$ @kbd{tar --list --file=collection.tar}
@var{archive-name}}) option just as with @option{--create}
(@option{-c}) to specify the name of the archive.
-@opindex list, using with @option{--verbose}
-@opindex verbose, using with @option{--list}
+@xopindex{list, using with @option{--verbose}}
+@xopindex{verbose, using with @option{--list}}
If you use the @option{--verbose} (@option{-v}) option with
@option{--list}, then @command{tar} will print out a listing
-reminiscent of @w{@samp{ls -l}}, showing owner, file size, and so forth.
+reminiscent of @w{@samp{ls -l}}, showing owner, file size, and so
+forth. This output is described in detail in @ref{verbose member listing}.
If you had used @option{--verbose} (@option{-v}) mode, the example
above would look like:
@end table
@cindex File name arguments, using @option{--list} with
-@opindex list, using with file name arguments
+@xopindex{list, using with file name arguments}
You can specify one or more individual member names as arguments when
using @samp{list}. In this case, @command{tar} will only list the
names of members you identify. For example, @w{@kbd{tar --list
--file=afiles.tar apple}} would only print @file{apple}.
Because @command{tar} preserves paths, file names must be specified as
-they appear in the archive (ie., relative to the directory from which
+they appear in the archive (i.e., relative to the directory from which
the archive was created). Therefore, it is essential when specifying
member names to @command{tar} that you give the exact member names.
For example, @w{@kbd{tar --list --file=bfiles.tar birds}} would produce an
to note these differences, and only use the option style(s) which
makes the most sense to you until you feel comfortable with the others.
-Some options @emph{may} take an argument (currently, there are
-two such options: @option{--backup} and @option{--occurrence}). Such
-options may have at most long and short forms, they do not have old style
-equivalent. The rules for specifying an argument for such options
-are stricter than those for specifying mandatory arguments. Please,
-pay special attention to them.
+Some options @emph{may} take an argument. Such options may have at
+most long and short forms, they do not have old style equivalent. The
+rules for specifying an argument for such options are stricter than
+those for specifying mandatory arguments. Please, pay special
+attention to them.
@menu
-* Mnemonic Options:: Mnemonic Option Style
+* Long Options:: Long Option Style
* Short Options:: Short Option Style
* Old Options:: Old Option Style
* Mixing:: Mixing Option Styles
@end menu
-@node Mnemonic Options
-@subsection Mnemonic Option Style
+@node Long Options
+@subsection Long Option Style
-@FIXME{have to decide whether or not to replace other occurrences of
-"mnemonic" with "long", or *ugh* vice versa.}
-
-Each option has at least one long (or mnemonic) name starting with two
+Each option has at least one @dfn{long} (or @dfn{mnemonic}) name starting with two
dashes in a row, e.g., @option{--list}. The long names are more clear than
their corresponding short or old names. It sometimes happens that a
-single mnemonic option has many different different names which are
+single long option has many different different names which are
synonymous, such as @option{--compare} and @option{--diff}. In addition,
long option names can be given unique abbreviations. For example,
@option{--cre} can be used in place of @option{--create} because there is no
-other mnemonic option which begins with @samp{cre}. (One way to find
+other long option which begins with @samp{cre}. (One way to find
this out is by trying it and seeing what happens; if a particular
abbreviation could represent more than one option, @command{tar} will tell
you that that abbreviation is ambiguous and you'll know that that
unique abbreviation for the long name of an option you didn't want to
use, you are stuck; @command{tar} will perform the command as ordered.)
-Mnemonic options are meant to be obvious and easy to remember, and their
+Long options are meant to be obvious and easy to remember, and their
meanings are generally easier to discern than those of their
corresponding short options (see below). For example:
gives a fairly good set of hints about what the command does, even
for those not fully acquainted with @command{tar}.
-Mnemonic options which require arguments take those arguments
+Long options which require arguments take those arguments
immediately following the option name. There are two ways of
specifying a mandatory argument. It can be separated from the
option name either by an equal sign, or by any amount of
@node Short Options
@subsection Short Option Style
-Most options also have a short option name. Short options start with
+Most options also have a @dfn{short option} name. Short options start with
a single dash, and are followed by a single character, e.g., @option{-t}
(which is equivalent to @option{--list}). The forms are absolutely
identical in function; they are interchangeable.
@subsection Old Option Style
@UNREVISED
-Like short options, old options are single letters. However, old options
+Like short options, @dfn{old options} are single letters. However, old options
must be written together as a single clumped set, without spaces separating
them or dashes preceding them@footnote{Beware that if you precede options
with a dash, you are announcing the short option style instead of the
anywhere else. The letter of an old option is exactly the same letter as
the corresponding short option. For example, the old option @samp{t} is
the same as the short option @option{-t}, and consequently, the same as the
-mnemonic option @option{--list}. So for example, the command @w{@samp{tar
+long option @option{--list}. So for example, the command @w{@samp{tar
cv}} specifies the option @option{-v} in addition to the operation @option{-c}.
When options that need arguments are given together with the command,
All three styles may be intermixed in a single @command{tar} command,
so long as the rules for each style are fully
respected@footnote{Before @GNUTAR{} version 1.11.6,
-a bug prevented intermixing old style options with mnemonic options in
+a bug prevented intermixing old style options with long options in
some cases.}. Old style options and either of the modern styles of
options may be mixed within a single @command{tar} command. However,
old style options must be introduced as the first arguments only,
@table @option
-@opindex append, summary
+@opsummary{append}
@item --append
@itemx -r
Appends files to the end of the archive. @xref{append}.
-@opindex catenate, summary
+@opsummary{catenate}
@item --catenate
@itemx -A
Same as @option{--concatenate}. @xref{concatenate}.
-@opindex compare, summary
+@opsummary{compare}
@item --compare
@itemx -d
system, and reports differences in file size, mode, owner,
modification date and contents. @xref{compare}.
-@opindex concatenate, summary
+@opsummary{concatenate}
@item --concatenate
@itemx -A
Appends other @command{tar} archives to the end of the archive.
@xref{concatenate}.
-@opindex create, summary
+@opsummary{create}
@item --create
@itemx -c
Creates a new @command{tar} archive. @xref{create}.
-@opindex delete, summary
+@opsummary{delete}
@item --delete
Deletes members from the archive. Don't try this on a archive on a
tape! @xref{delete}.
-@opindex diff, summary
+@opsummary{diff}
@item --diff
@itemx -d
Same @option{--compare}. @xref{compare}.
-@opindex extract, summary
+@opsummary{extract}
@item --extract
@itemx -x
Extracts members from the archive into the file system. @xref{extract}.
-@opindex get, summary
+@opsummary{get}
@item --get
@itemx -x
Same as @option{--extract}. @xref{extract}.
-@opindex list, summary
+@opsummary{list}
@item --list
@itemx -t
Lists the members in an archive. @xref{list}.
-@opindex update, summary
+@opsummary{update}
@item --update
@itemx -u
@table @option
-@opindex absolute-names, summary
+@opsummary{absolute-names}
@item --absolute-names
@itemx -P
@samp{/} from member names. This option disables that behavior.
@xref{absolute}.
-@opindex after-date, summary
+@opsummary{after-date}
@item --after-date
(See @option{--newer}, @pxref{after})
-@opindex anchored, summary
+@opsummary{anchored}
@item --anchored
A pattern must match an initial subsequence of the name's components.
@xref{controlling pattern-matching}.
-@opindex atime-preserve, summary
+@opsummary{atime-preserve}
@item --atime-preserve
@itemx --atime-preserve=replace
@itemx --atime-preserve=system
as support for @option{--atime-preserve=system} improves.
If your operating system does not support
-@option{--atime-preserve=system}, you might be able to preserve access
+@option{--atime-preserve=@-system}, you might be able to preserve access
times reliably by by using the @command{mount} command. For example,
you can mount the file system read-only, or access the file system via
a read-only loopback mount, or use the @samp{noatime} mount option
available on some systems. However, mounting typically requires
superuser privileges and can be a pain to manage.
-@opindex backup, summary
+@opsummary{backup}
@item --backup=@var{backup-type}
Rather than deleting files from the file system, @command{tar} will
back them up using simple or numbered backups, depending upon
@var{backup-type}. @xref{backup}.
-@opindex block-number, summary
+@opsummary{block-number}
@item --block-number
@itemx -R
With this option present, @command{tar} prints error messages for read errors
with the block number in the archive file. @xref{block-number}.
-@opindex blocking-factor, summary
+@opsummary{blocking-factor}
@item --blocking-factor=@var{blocking}
@itemx -b @var{blocking}
Sets the blocking factor @command{tar} uses to @var{blocking} x 512 bytes per
record. @xref{Blocking Factor}.
-@opindex bzip2, summary
+@opsummary{bzip2}
@item --bzip2
@itemx -j
This option tells @command{tar} to read or write archives through
@code{bzip2}. @xref{gzip}.
-@opindex checkpoint, summary
-@item --checkpoint
+@opsummary{checkpoint}
+@item --checkpoint[=@var{number}]
-This option directs @command{tar} to print periodic checkpoint messages as it
-reads through the archive. It is intended for when you want a visual
-indication that @command{tar} is still running, but don't want to see
-@option{--verbose} output. @FIXME-xref{}
+This option directs @command{tar} to print periodic checkpoint
+messages as it reads through the archive. It is intended for when you
+want a visual indication that @command{tar} is still running, but
+don't want to see @option{--verbose} output. For a detailed
+description, see @ref{Progress information}.
-@opindex check-links, summary
+@opsummary{check-links}
@item --check-links
@itemx -l
If this option was given, @command{tar} will check the number of links
dumped for each processed file. If this number does not match the
total number of hard links for the file, a warning message will be
output @footnote{Earlier versions of @GNUTAR{} understood @option{-l} as a
-synonym for @option{--one-file-system}. The current semantics, wich
+synonym for @option{--one-file-system}. The current semantics, which
complies to UNIX98, was introduced with version
1.15.91. @xref{Changes}, for more information.}.
-@opindex compress, summary
-@opindex uncompress, summary
+@opsummary{compress}
+@opsummary{uncompress}
@item --compress
@itemx --uncompress
@itemx -Z
writing the archive. This allows you to directly act on archives
while saving space. @xref{gzip}.
-@opindex confirmation, summary
+@opsummary{confirmation}
@item --confirmation
(See @option{--interactive}.) @xref{interactive}.
-@opindex delay-directory-restore, summary
+@opsummary{delay-directory-restore}
@item --delay-directory-restore
Delay setting modification times and permissions of extracted
directories until the end of extraction. @xref{Directory Modification Times and Permissions}.
-@opindex dereference, summary
+@opsummary{dereference}
@item --dereference
@itemx -h
file that a symbolic link points to, rather than archiving the
symlink. @xref{dereference}.
-@opindex directory, summary
+@opsummary{directory}
@item --directory=@var{dir}
@itemx -C @var{dir}
to @var{dir} before performing any operations. When this option is used
during archive creation, it is order sensitive. @xref{directory}.
-@opindex exclude, summary
+@opsummary{exclude}
@item --exclude=@var{pattern}
When performing operations, @command{tar} will skip files that match
@var{pattern}. @xref{exclude}.
-@opindex exclude-from, summary
+@opsummary{exclude-from}
@item --exclude-from=@var{file}
@itemx -X @var{file}
Similar to @option{--exclude}, except @command{tar} will use the list of
patterns in the file @var{file}. @xref{exclude}.
-@opindex exclude-caches, summary
+@opsummary{exclude-caches}
@item --exclude-caches
Automatically excludes all directories
containing a cache directory tag. @xref{exclude}.
-@opindex file, summary
+@opsummary{file}
@item --file=@var{archive}
@itemx -f @var{archive}
performs operations on, rather than @command{tar}'s compilation dependent
default. @xref{file tutorial}.
-@opindex files-from, summary
+@opsummary{files-from}
@item --files-from=@var{file}
@itemx -T @var{file}
or files to operate on, in addition to those specified on the
command-line. @xref{files}.
-@opindex force-local, summary
+@opsummary{force-local}
@item --force-local
Forces @command{tar} to interpret the filename given to @option{--file}
as a local file, even if it looks like a remote tape drive name.
@xref{local and remote archives}.
-@opindex format, summary
+@opsummary{format}
@item --format=@var{format}
+@itemx -H @var{format}
Selects output archive format. @var{Format} may be one of the
following:
@xref{Formats}, for a detailed discussion of these formats.
-@opindex group, summary
+@opsummary{group}
@item --group=@var{group}
Files added to the @command{tar} archive will have a group id of @var{group},
rather than the group from the source file. @var{group} is first decoded
as a group symbolic name, but if this interpretation fails, it has to be
-a decimal numeric group ID. @FIXME-xref{}
+a decimal numeric group ID. @xref{override}.
Also see the comments for the @option{--owner=@var{user}} option.
-@opindex gzip, summary
-@opindex gunzip, summary
-@opindex ungzip, summary
+@opsummary{gzip}
+@opsummary{gunzip}
+@opsummary{ungzip}
@item --gzip
@itemx --gunzip
@itemx --ungzip
@command{gzip}, allowing @command{tar} to directly operate on several
kinds of compressed archives transparently. @xref{gzip}.
-@opindex help, summary
+@opsummary{help}
@item --help
+@itemx -?
@command{tar} will print out a short message summarizing the operations and
options to @command{tar} and exit. @xref{help}.
-@opindex ignore-case, summary
+@opsummary{ignore-case}
@item --ignore-case
Ignore case when matching member or file names with
patterns. @xref{controlling pattern-matching}.
-@opindex ignore-command-error, summary
+@opsummary{ignore-command-error}
@item --ignore-command-error
Ignore exit codes of subprocesses. @xref{Writing to an External Program}.
-@opindex ignore-failed-read, summary
+@opsummary{ignore-failed-read}
@item --ignore-failed-read
Do not exit unsuccessfully merely because an unreadable file was encountered.
@xref{Reading}.
-@opindex ignore-zeros, summary
+@opsummary{ignore-zeros}
@item --ignore-zeros
@itemx -i
With this option, @command{tar} will ignore zeroed blocks in the
archive, which normally signals EOF. @xref{Reading}.
-@opindex incremental, summary
+@opsummary{incremental}
@item --incremental
@itemx -G
primarily for backwards compatibility only. @xref{Incremental Dumps},
for a detailed discussion of incremental archives.
-@opindex index-file, summary
+@opsummary{index-file}
@item --index-file=@var{file}
Send verbose output to @var{file} instead of to standard output.
-@opindex info-script, summary
-@opindex new-volume-script, summary
+@opsummary{info-script}
+@opsummary{new-volume-script}
@item --info-script=@var{script-file}
@itemx --new-volume-script=@var{script-file}
@itemx -F @var{script-file}
@command{tar} fails immediately. @xref{info-script}, for a detailed
discussion of @var{script-file}.
-@opindex interactive, summary
+@opsummary{interactive}
@item --interactive
@itemx --confirmation
@itemx -w
performing potentially destructive options, such as overwriting files.
@xref{interactive}.
-@opindex keep-newer-files, summary
+@opsummary{keep-newer-files}
@item --keep-newer-files
Do not replace existing files that are newer than their archive copies
when extracting files from an archive.
-@opindex keep-old-files, summary
+@opsummary{keep-old-files}
@item --keep-old-files
@itemx -k
Do not overwrite existing files when extracting files from an archive.
@xref{Keep Old Files}.
-@opindex label, summary
+@opsummary{label}
@item --label=@var{name}
@itemx -V @var{name}
@command{tar} will only operate on archives that have a label matching
the pattern specified in @var{name}. @xref{Tape Files}.
-@opindex listed-incremental, summary
+@opsummary{listed-incremental}
@item --listed-incremental=@var{snapshot-file}
@itemx -g @var{snapshot-file}
With other operations, informs @command{tar} that the archive is in
incremental format. @xref{Incremental Dumps}.
-@opindex mode, summary
+@opsummary{mode}
@item --mode=@var{permissions}
When adding files to an archive, @command{tar} will use
@var{permissions} for the archive members, rather than the permissions
-from the files. The program @command{chmod} and this @command{tar}
-option share the same syntax for what @var{permissions} might be.
-@xref{File permissions, Permissions, File permissions, fileutils,
-@acronym{GNU} file utilities}. This reference also has useful
-information for those not being overly familiar with the Unix
-permission system.
-
-Of course, @var{permissions} might be plainly specified as an octal number.
-However, by using generic symbolic modifications to mode bits, this allows
-more flexibility. For example, the value @samp{a+rw} adds read and write
-permissions for everybody, while retaining executable bits on directories
-or on any other file already marked as executable.
+from the files. @var{permissions} can be specified either as an octal
+number or as symbolic permissions, like with
+@command{chmod}. @xref{override}.
+
+@opsummary{mtime}
+@item --mtime=@var{date}
-@opindex multi-volume, summary
+When adding files to an archive, @command{tar} will use @var{date} as
+the modification time of members when creating archives, instead of
+their actual modification times. The value of @var{date} can be
+either a textual date representation (@pxref{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. @xref{override}.
+
+@opsummary{multi-volume}
@item --multi-volume
@itemx -M
Informs @command{tar} that it should create or otherwise operate on a
multi-volume @command{tar} archive. @xref{Using Multiple Tapes}.
-@opindex new-volume-script, summary
+@opsummary{new-volume-script}
@item --new-volume-script
(see --info-script)
-@opindex seek, summary
+@opsummary{seek}
@item --seek
@itemx -n
the archive can be seeked or not. This option is intended for use
in cases when such recognition fails.
-@opindex newer, summary
+@opsummary{newer}
@item --newer=@var{date}
@itemx --after-date=@var{date}
@itemx -N
is taken to be the name of a file whose data modification time specifies
the date. @xref{after}.
-@opindex newer-mtime, summary
+@opsummary{newer-mtime}
@item --newer-mtime=@var{date}
Like @option{--newer}, but add only files whose
contents have changed (as opposed to just @option{--newer}, which will
-also back up files for which any status information has changed).
+also back up files for which any status information has
+changed). @xref{after}.
-@opindex no-anchored, summary
+@opsummary{no-anchored}
@item --no-anchored
An exclude pattern can match any subsequence of the name's components.
@xref{controlling pattern-matching}.
-@opindex no-delay-directory-restore, summary
+@opsummary{no-delay-directory-restore}
@item --no-delay-directory-restore
Setting modification times and permissions of extracted
directories when all files from this directory has been
extracted. This is the default. @xref{Directory Modification Times and Permissions}.
-@opindex no-ignore-case, summary
+@opsummary{no-ignore-case}
@item --no-ignore-case
Use case-sensitive matching.
@xref{controlling pattern-matching}.
-@opindex no-ignore-command-error, summary
+@opsummary{no-ignore-command-error}
@item --no-ignore-command-error
Print warnings about subprocesses terminated with a non-zero exit
code. @xref{Writing to an External Program}.
-@opindex no-quote-chars, summary
+@opsummary{no-overwrite-dir}
+@item --no-overwrite-dir
+
+Preserve metadata of existing directories when extracting files
+from an archive. @xref{Overwrite Old Files}.
+
+@opsummary{no-quote-chars}
@item --no-quote-chars=@var{string}
Remove characters listed in @var{string} from the list of quoted
characters set by the previous @option{--quote-chars} option
(@pxref{quoting styles}).
-@opindex no-recursion, summary
+@opsummary{no-recursion}
@item --no-recursion
With this option, @command{tar} will not recurse into directories.
@xref{recurse}.
-@opindex no-same-owner, summary
+@opsummary{no-same-owner}
@item --no-same-owner
@itemx -o
specified in the @command{tar} archive. This the default behavior
for ordinary users.
-@opindex no-same-permissions, summary
+@opsummary{no-same-permissions}
@item --no-same-permissions
When extracting an archive, subtract the user's umask from files from
the permissions specified in the archive. This is the default behavior
for ordinary users.
-@opindex no-wildcards, summary
+@opsummary{no-unquote}
+@item --no-unquote
+Treat all input file or member names literally, do not interpret
+escape sequences. @xref{input name quoting}.
+
+@opsummary{no-wildcards}
@item --no-wildcards
Do not use wildcards.
@xref{controlling pattern-matching}.
-@opindex no-wildcards-match-slash, summary
+@opsummary{no-wildcards-match-slash}
@item --no-wildcards-match-slash
Wildcards do not match @samp{/}.
@xref{controlling pattern-matching}.
-@opindex null, summary
+@opsummary{null}
@item --null
When @command{tar} is using the @option{--files-from} option, this option
@command{tar} can correctly work with file names that contain newlines.
@xref{nul}.
-@opindex numeric-owner, summary
+@opsummary{numeric-owner}
@item --numeric-owner
This option will notify @command{tar} that it should use numeric user
@xref{Attributes}.
@item -o
-When extracting files, this option is a synonym for
+The function of this option depends on the action @command{tar} is
+performing. When extracting files, @option{-o} is a synonym for
@option{--no-same-owner}, i.e. it prevents @command{tar} from
restoring ownership of files being extracted.
-When creating an archive, @option{-o} is a synonym for
+When creating an archive, it is a synonym for
@option{--old-archive}. This behavior is for compatibility
with previous versions of @GNUTAR{}, and will be
removed in the future releases.
@xref{Changes}, for more information.
-@opindex occurrence, summary
+@opsummary{occurrence}
@item --occurrence[=@var{number}]
This option can be used in conjunction with one of the subcommands
@end smallexample
@noindent
-will extract the first occurrence of @file{filename} from @file{archive.tar}
+will extract the first occurrence of the member @file{filename} from @file{archive.tar}
and will terminate without scanning to the end of the archive.
-@opindex old-archive, summary
+@opsummary{old-archive}
@item --old-archive
Synonym for @option{--format=v7}.
-@opindex one-file-system, summary
+@opsummary{one-file-system}
@item --one-file-system
Used when creating an archive. Prevents @command{tar} from recursing into
directories that are on different file systems from the current
synonym for @option{--one-file-system}. This has changed in version
1.15.91. @xref{Changes}, for more information.}.
-@opindex overwrite, summary
+@opsummary{overwrite}
@item --overwrite
Overwrite existing files and directory metadata when extracting files
from an archive. @xref{Overwrite Old Files}.
-@opindex overwrite-dir, summary
+@opsummary{overwrite-dir}
@item --overwrite-dir
Overwrite the metadata of existing directories when extracting files
from an archive. @xref{Overwrite Old Files}.
-@opindex owner, summary
+@opsummary{owner}
@item --owner=@var{user}
Specifies that @command{tar} should use @var{user} as the owner of members
when creating archives, instead of the user associated with the source
file. @var{user} is first decoded as a user symbolic name, but if
this interpretation fails, it has to be a decimal numeric user ID.
-@FIXME-xref{}
-
-There is no value indicating a missing number, and @samp{0} usually means
-@code{root}. Some people like to force @samp{0} as the value to offer in
-their distributions for the owner of files, because the @code{root} user is
-anonymous anyway, so that might as well be the owner of anonymous archives.
+@xref{override}.
This option does not affect extraction from archives.
-@opindex transform, summary
+@opsummary{transform}
@item --transform=@var{sed-expr}
Transform file or member names using @command{sed} replacement expression
@option{--show-transformed-names} option
(@pxref{show-transformed-names}).
-@opindex quote-chars, summary
+@opsummary{quote-chars}
@item --quote-chars=@var{string}
Always quote characters from @var{string}, even if the selected
quoting style would not quote them (@pxref{quoting styles}).
-@opindex quoting-style, summary
+@opsummary{quoting-style}
@item --quoting-style=@var{style}
Set quoting style to use when printing member and file names
(@pxref{quoting styles}). Valid @var{style} values are:
style is @code{escape}, unless overridden while configuring the
package.
-@opindex pax-option, summary
+@opsummary{pax-option}
@item --pax-option=@var{keyword-list}
-@FIXME{Such a detailed description does not belong there, move it elsewhere.}
This option is meaningful only with @acronym{POSIX.1-2001} archives
(@pxref{posix}). It modifies the way @command{tar} handles the
extended header keywords. @var{Keyword-list} is a comma-separated
-list of keyword options, each keyword option taking one of
-the following forms:
-
-@table @asis
-@item delete=@var{pattern}
-When used with one of archive-creation commands,
-this option instructs @command{tar} to omit from extended header records
-that it produces any keywords matching the string @var{pattern}.
-
-When used in extract or list mode, this option instructs tar
-to ignore any keywords matching the given @var{pattern} in the extended
-header records. In both cases, matching is performed using the pattern
-matching notation described in @acronym{POSIX 1003.2}, 3.13
-(See @cite{glob(7)}). For example:
-
-@smallexample
---pax-option delete=security.*
-@end smallexample
-
-would suppress security-related information.
-
-@item exthdr.name=@var{string}
-
-This keyword allows user control over the name that is written into the
-ustar header blocks for the extended headers. The name is obtained
-from @var{string} after making the following substitutions:
-
-@multitable @columnfractions .30 .70
-@headitem Meta-character @tab Replaced By
-@item %d @tab The directory name of the file, equivalent to the
-result of the @command{dirname} utility on the translated pathname.
-@item %f @tab The filename of the file, equivalent to the result
-of the @command{basename} utility on the translated pathname.
-@item %p @tab The process ID of the @command{tar} process.
-@item %% @tab A @samp{%} character.
-@end multitable
-
-Any other @samp{%} characters in @var{string} produce undefined
-results.
-
-If no option @samp{exthdr.name=string} is specified, @command{tar}
-will use the following default value:
-
-@smallexample
-%d/PaxHeaders.%p/%f
-@end smallexample
-
-@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
-is obtained from the contents of @var{string}, after making
-the following substitutions:
-
-@multitable @columnfractions .30 .70
-@headitem Meta-character @tab Replaced By
-@item %n @tab An integer that represents the
-sequence number of the global extended header record in the archive,
-starting at 1.
-@item %p @tab The process ID of the @command{tar} process.
-@item %% @tab A @samp{%} character.
-@end multitable
-
-Any other @samp{%} characters in @var{string} produce undefined results.
-
-If no option @samp{globexthdr.name=string} is specified, @command{tar}
-will use the following default value:
-
-@smallexample
-$TMPDIR/GlobalHead.%p.%n
-@end smallexample
+list of keyword options. @xref{PAX keywords}, for a detailed
+discussion.
-@noindent
-where @samp{$TMPDIR} represents the value of the @var{TMPDIR}
-environment variable. If @var{TMPDIR} is not set, @command{tar}
-uses @samp{/tmp}.
-
-@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
-header record. When used with one of archive-reading commands,
-@command{tar} will behave as if it has encountered these keyword/value
-pairs at the beginning of the archive in a global extended header
-record.
-
-@item @var{keyword}:=@var{value}
-When used with one of archive-creation commands, these keyword/value pairs
-will be included as records at the beginning of an extended header for
-each file. This is effectively equivalent to @var{keyword}=@var{value}
-form except that it creates no global extended header records.
-
-When used with one of archive-reading commands, @command{tar} will
-behave as if these keyword/value pairs were included as records at the
-end of each extended header; thus, they will override any global or
-file-specific extended header record keywords of the same names.
-For example, in the command:
-
-@smallexample
-tar --format=posix --create \
- --file archive --pax-option gname:=user .
-@end smallexample
-
-the group name will be forced to a new value for all files
-stored in the archive.
-@end table
-
-@opindex portability, summary
+@opsummary{portability}
@item --portability
@itemx --old-archive
Synonym for @option{--format=v7}.
-@opindex posix, summary
+@opsummary{posix}
@item --posix
Same as @option{--format=posix}.
-@opindex preserve, summary
+@opsummary{preserve}
@item --preserve
Synonymous with specifying both @option{--preserve-permissions} and
@option{--same-order}. @xref{Setting Access Permissions}.
-@opindex preserve-order, summary
+@opsummary{preserve-order}
@item --preserve-order
(See @option{--same-order}; @pxref{Reading}.)
-@opindex preserve-permissions, summary
-@opindex same-permissions, summary
+@opsummary{preserve-permissions}
+@opsummary{same-permissions}
@item --preserve-permissions
@itemx --same-permissions
@itemx -p
Specifying this option instructs @command{tar} that it should use the
permissions directly from the archive. @xref{Setting Access Permissions}.
-@opindex read-full-records, summary
+@opsummary{read-full-records}
@item --read-full-records
@itemx -B
Specifies that @command{tar} should reblock its input, for reading
from pipes on systems with buggy implementations. @xref{Reading}.
-@opindex record-size, summary
+@opsummary{record-size}
@item --record-size=@var{size}
Instructs @command{tar} to use @var{size} bytes per record when accessing the
archive. @xref{Blocking Factor}.
-@opindex recursion, summary
+@opsummary{recursion}
@item --recursion
With this option, @command{tar} recurses into directories.
@xref{recurse}.
-@opindex recursive-unlink, summary
+@opsummary{recursive-unlink}
@item --recursive-unlink
Remove existing
directory hierarchies before extracting directories of the same name
from the archive. @xref{Recursive Unlink}.
-@opindex remove-files, summary
+@opsummary{remove-files}
@item --remove-files
Directs @command{tar} to remove the source file from the file system after
appending it to an archive. @xref{remove files}.
-@opindex restrict, summary
+@opsummary{restrict}
@item --restrict
Disable use of some potentially harmful @command{tar} options.
Currently this option disables shell invocaton from multi-volume menu
(@pxref{Using Multiple Tapes}).
-@opindex rmt-command, summary
+@opsummary{rmt-command}
@item --rmt-command=@var{cmd}
Notifies @command{tar} that it should use @var{cmd} instead of
the default @file{/usr/libexec/rmt} (@pxref{Remote Tape Server}).
-@opindex rsh-command, summary
+@opsummary{rsh-command}
@item --rsh-command=@var{cmd}
Notifies @command{tar} that is should use @var{cmd} to communicate with remote
devices. @xref{Device}.
-@opindex same-order, summary
+@opsummary{same-order}
@item --same-order
@itemx --preserve-order
@itemx -s
arguments has already been sorted to match the order of files in the
archive. @xref{Reading}.
-@opindex same-owner, summary
+@opsummary{same-owner}
@item --same-owner
When extracting an archive, @command{tar} will attempt to preserve the owner
This is the default behavior for the superuser; this option has an
effect only for ordinary users. @xref{Attributes}.
-@opindex same-permissions, summary
+@opsummary{same-permissions}
@item --same-permissions
(See @option{--preserve-permissions}; @pxref{Setting Access Permissions}.)
-@opindex show-defaults, summary
+@opsummary{show-defaults}
@item --show-defaults
Displays the default options used by @command{tar} and exits
--rmt-command=/usr/libexec/rmt --rsh-command=/usr/bin/rsh
@end smallexample
-@opindex show-omitted-dirs, summary
+@opsummary{show-omitted-dirs}
@item --show-omitted-dirs
Instructs @command{tar} to mention directories its skipping over when
operating on a @command{tar} archive. @xref{show-omitted-dirs}.
-@opindex show-transformed-names, summary
-@opindex show-stored-names, summary
+@opsummary{show-transformed-names}
+@opsummary{show-stored-names}
@item --show-transformed-names
@itemx --show-stored-names
stored in the archive, as opposed to the actual file
names. @xref{listing member and file names}.
-@opindex sparse, summary
+@opsummary{sparse}
@item --sparse
@itemx -S
Invokes a @acronym{GNU} extension when adding files to an archive that handles
sparse files efficiently. @xref{sparse}.
-@opindex starting-file, summary
+@opsummary{starting-file}
@item --starting-file=@var{name}
@itemx -K @var{name}
files in the archive until it finds one that matches @var{name}.
@xref{Scarce}.
-@opindex strip-components, summary
+@opsummary{strip-components}
@item --strip-components=@var{number}
Strip given @var{number} of leading components from file names before
extraction.@footnote{This option was called @option{--strip-path} in
@noindent
would extract this file to file @file{name}.
-@opindex suffix, summary
+@opsummary{suffix}, summary
@item --suffix=@var{suffix}
Alters the suffix @command{tar} uses when backing up files from the default
@samp{~}. @xref{backup}.
-@opindex tape-length, summary
+@opsummary{tape-length}
@item --tape-length=@var{num}
@itemx -L @var{num}
Specifies the length of tapes that @command{tar} is writing as being
@w{@var{num} x 1024} bytes long. @xref{Using Multiple Tapes}.
-@opindex test-label, summary
+@opsummary{test-label}
@item --test-label
Reads the volume label. If an argument is specified, test whether it
matches the volume label. @xref{--test-label option}.
-@opindex to-command, summary
+@opsummary{to-command}
@item --to-command=@var{command}
During extraction @command{tar} will pipe extracted files to the
-standard input of @var{command}. @xref{Writing to an External Program}.
+standard input of @var{command}. @xref{Writing to an External Program}.
-@opindex to-stdout, summary
+@opsummary{to-stdout}
@item --to-stdout
@itemx -O
During extraction, @command{tar} will extract files to stdout rather
than to the file system. @xref{Writing to Standard Output}.
-@opindex totals, summary
-@item --totals
+@opsummary{totals}
+@item --totals[=@var{signo}]
-Displays the total number of bytes written after creating an archive.
-@xref{verbose}.
+Displays the total number of bytes transferred when processing an
+archive. If an argument is given, these data are displayed on
+request, when signal @var{signo} is delivered to @command{tar}.
+@xref{totals}.
-@opindex touch, summary
+@opsummary{touch}
@item --touch
@itemx -m
rather than the data modification time stored in the archive.
@xref{Data Modification Times}.
-@opindex uncompress, summary
+@opsummary{uncompress}
@item --uncompress
(See @option{--compress}. @pxref{gzip})
-@opindex ungzip, summary
+@opsummary{ungzip}
@item --ungzip
(See @option{--gzip}. @pxref{gzip})
-@opindex unlink-first, summary
+@opsummary{unlink-first}
@item --unlink-first
@itemx -U
Directs @command{tar} to remove the corresponding file from the file
system before extracting it from the archive. @xref{Unlink First}.
-@opindex use-compress-program, summary
+@opsummary{unquote}
+@item --unquote
+Enable unquoting input file or member names (default). @xref{input
+name quoting}.
+
+@opsummary{use-compress-program}
@item --use-compress-program=@var{prog}
Instructs @command{tar} to access the archive through @var{prog}, which is
presumed to be a compression program of some sort. @xref{gzip}.
-@opindex utc, summary
+@opsummary{utc}
@item --utc
Display file modification dates in @acronym{UTC}. This option implies
@option{--verbose}.
-@opindex verbose, summary
+@opsummary{verbose}
@item --verbose
@itemx -v
operations to increase the amount of information displayed.
@xref{verbose}.
-@opindex verify, summary
+@opsummary{verify}
@item --verify
@itemx -W
Verifies that the archive was correctly written when creating an
archive. @xref{verify}.
-@opindex version, summary
+@opsummary{version}
@item --version
Print information about the program's name, version, origin and legal
status, all on standard output, and then exit successfully.
@xref{help}.
-@opindex volno-file, summary
+@opsummary{volno-file}
@item --volno-file=@var{file}
-Used in conjunction with @option{--multi-volume}. @command{tar} will keep track
-of which volume of a multi-volume archive its working in @var{file}.
-@xref{volno-file}.
+Used in conjunction with @option{--multi-volume}. @command{tar} will
+keep track of which volume of a multi-volume archive its working in
+@var{file}. @xref{volno-file}.
-@opindex wildcards, summary
+@opsummary{wildcards}
@item --wildcards
Use wildcards when matching member names with patterns.
@xref{controlling pattern-matching}.
-@opindex wildcards-match-slash, summary
+@opsummary{wildcards-match-slash}
@item --wildcards-match-slash
Wildcards match @samp{/}.
@xref{controlling pattern-matching}.
Here is an alphabetized list of all of the short option forms, matching
them with the equivalent long option.
-@table @option
-
-@item -A
-
-@option{--concatenate}
-
-@item -B
-
-@option{--read-full-records}
-
-@item -C
-
-@option{--directory}
-
-@item -F
-
-@option{--info-script}
-
-@item -G
-
-@option{--incremental}
-
-@item -K
-
-@option{--starting-file}
-
-@item -L
-
-@option{--tape-length}
-
-@item -M
-
-@option{--multi-volume}
-
-@item -N
-
-@option{--newer}
-
-@item -O
-
-@option{--to-stdout}
-
-@item -P
-
-@option{--absolute-names}
-
-@item -R
-
-@option{--block-number}
-
-@item -S
-
-@option{--sparse}
-
-@item -T
-
-@option{--files-from}
-
-@item -U
-
-@option{--unlink-first}
-
-@item -V
+@multitable @columnfractions 0.20 0.80
+@headitem Short Option @tab Reference
-@option{--label}
+@item -A @tab @ref{--concatenate}.
-@item -W
-
-@option{--verify}
+@item -B @tab @ref{--read-full-records}.
-@item -X
+@item -C @tab @ref{--directory}.
-@option{--exclude-from}
+@item -F @tab @ref{--info-script}.
-@item -Z
+@item -G @tab @ref{--incremental}.
-@option{--compress}
+@item -K @tab @ref{--starting-file}.
-@item -b
+@item -L @tab @ref{--tape-length}.
-@option{--blocking-factor}
+@item -M @tab @ref{--multi-volume}.
-@item -c
+@item -N @tab @ref{--newer}.
-@option{--create}
+@item -O @tab @ref{--to-stdout}.
-@item -d
+@item -P @tab @ref{--absolute-names}.
-@option{--compare}
+@item -R @tab @ref{--block-number}.
-@item -f
+@item -S @tab @ref{--sparse}.
-@option{--file}
+@item -T @tab @ref{--files-from}.
-@item -g
+@item -U @tab @ref{--unlink-first}.
-@option{--listed-incremental}
+@item -V @tab @ref{--label}.
-@item -h
+@item -W @tab @ref{--verify}.
-@option{--dereference}
+@item -X @tab @ref{--exclude-from}.
-@item -i
+@item -Z @tab @ref{--compress}.
-@option{--ignore-zeros}
+@item -b @tab @ref{--blocking-factor}.
-@item -j
+@item -c @tab @ref{--create}.
-@option{--bzip2}
+@item -d @tab @ref{--compare}.
-@item -k
+@item -f @tab @ref{--file}.
-@option{--keep-old-files}
+@item -g @tab @ref{--listed-incremental}.
-@item -l
+@item -h @tab @ref{--dereference}.
-@option{--one-file-system}. Use of this short option is deprecated. It
-is retained for compatibility with the earlier versions of GNU
-@command{tar}, and will be changed in future releases.
+@item -i @tab @ref{--ignore-zeros}.
-@xref{Changes}, for more information.
+@item -j @tab @ref{--bzip2}.
-@item -m
+@item -k @tab @ref{--keep-old-files}.
-@option{--touch}
+@item -l @tab @ref{--check-links}.
-@item -o
+@item -m @tab @ref{--touch}.
-When creating --- @option{--no-same-owner}, when extracting ---
-@option{--portability}.
+@item -o @tab When creating, @ref{--no-same-owner}, when extracting ---
+@ref{--portability}.
The later usage is deprecated. It is retained for compatibility with
the earlier versions of @GNUTAR{}. In the future releases
@option{-o} will be equivalent to @option{--no-same-owner} only.
-@item -p
-
-@option{--preserve-permissions}
-
-@item -r
-
-@option{--append}
-
-@item -s
-
-@option{--same-order}
+@item -p @tab @ref{--preserve-permissions}.
-@item -t
+@item -r @tab @ref{--append}.
-@option{--list}
+@item -s @tab @ref{--same-order}.
-@item -u
+@item -t @tab @ref{--list}.
-@option{--update}
+@item -u @tab @ref{--update}.
-@item -v
+@item -v @tab @ref{--verbose}.
-@option{--verbose}
+@item -w @tab @ref{--interactive}.
-@item -w
+@item -x @tab @ref{--extract}.
-@option{--interactive}
+@item -z @tab @ref{--gzip}.
-@item -x
-
-@option{--extract}
-
-@item -z
-
-@option{--gzip}
-
-@end table
+@end multitable
@node help
@section @GNUTAR{} documentation
successfully. For example, @w{@samp{tar --version}} might print:
@smallexample
-tar (GNU tar) 1.15.2
+tar (GNU tar) @value{VERSION}
Copyright (C) 2006 Free Software Foundation, Inc.
-This is free software. You may redistribute copies of it under the terms of
-the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
+This is free software. You may redistribute copies of it under the terms
+of the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
There is NO WARRANTY, to the extent permitted by law.
Written by John Gilmore and Jay Fenlason.
@cindex Obtaining help
@cindex Listing all @command{tar} options
-@opindex help, introduction
+@xopindex{help, introduction}
Another thing you might want to do is checking the spelling or meaning
of some particular @command{tar} option, without resorting to this
manual, for once you have carefully read it. @GNUTAR{}
back to the full documentation for precise points. If you are reading
this paragraph, you already have the @command{tar} manual in some
form. This manual is available in a variety of forms from
-@url{http://www.gnu.org/software/tar/manual}. It may printed out of the @GNUTAR{}
+@url{http://www.gnu.org/software/tar/manual}. It may be printed out of the @GNUTAR{}
distribution, provided you have @TeX{} already installed somewhere,
and a laser printer around. Just configure the distribution, execute
the command @w{@samp{make dvi}}, then print @file{doc/tar.dvi} the
@smallexample
@group
@kbd{tar --show-defaults}
---format=gnu -f- -b20 --rmt-command=/etc/rmt --rsh-command=/usr/bin/rsh
+--format=gnu -f- -b20 --quoting-style=escape
+--rmt-command=/etc/rmt --rsh-command=/usr/bin/rsh
@end group
@end smallexample
+@noindent
+Notice, that this option outputs only one line. The example output above
+has been split to fit page boundaries.
+
@noindent
The above output shows that this version of @GNUTAR{} defaults to
using @samp{gnu} archive format (@pxref{Formats}), it uses standard
With @option{--create} or @option{--extract}, @option{--verbose} used
once just prints the names of the files or members as they are processed.
Using it twice causes @command{tar} to print a longer listing
-(reminiscent of @samp{ls -l}) for each member. Since @option{--list}
-already prints the names of the members, @option{--verbose} used once
-with @option{--list} causes @command{tar} to print an @samp{ls -l}
-type listing of the files in the archive. The following examples both
-extract members with long list output:
+(@xref{verbose member listing}, for the description) for each member.
+Since @option{--list} already prints the names of the members,
+@option{--verbose} used once with @option{--list} causes @command{tar}
+to print an @samp{ls -l} type listing of the files in the archive.
+The following examples both extract members with long list output:
@smallexample
$ @kbd{tar --extract --file=archive.tar --verbose --verbose}
verbose output to @var{file} rather than to standard output or standard
error.
+@anchor{totals}
@cindex Obtaining total status information
@opindex totals
-The @option{--totals} option---which is only meaningful when used with
-@option{--create} (@option{-c})---causes @command{tar} to print the total
-amount written to the archive, after it has been fully created.
+The @option{--totals} option causes @command{tar} to print on the
+standard error the total amount of bytes transferred when processing
+an archive. When creating or appending to an archive, this option
+prints the number of bytes written to the archive and the average
+speed at which they have been written, e.g.:
+
+@smallexample
+@group
+$ @kbd{tar -c -f archive.tar --totals /home}
+Total bytes written: 7924664320 (7.4GiB, 85MiB/s)
+@end group
+@end smallexample
+
+When reading an archive, this option displays the number of bytes
+read:
+
+@smallexample
+@group
+$ @kbd{tar -x -f archive.tar --totals}
+Total bytes read: 7924664320 (7.4GiB, 95MiB/s)
+@end group
+@end smallexample
+
+Finally, when deleting from an archive, the @option{--totals} option
+displays both numbers plus number of bytes removed from the archive:
+
+@smallexample
+@group
+$ @kbd{tar --delete -f foo.tar --totals --wildcards '*~'}
+Total bytes read: 9543680 (9.2MiB, 201MiB/s)
+Total bytes written: 3829760 (3.7MiB, 81MiB/s)
+Total bytes deleted: 1474048
+@end group
+@end smallexample
+
+You can also obtain this information on request. When
+@option{--totals} is used with an argument, this argument is
+interpreted as a symbolic name of a signal, upon delivery of which the
+statistics is to be printed:
+
+@table @option
+@item --totals=@var{signo}
+Print statistics upon delivery of signal @var{signo}. Valid arguments
+are: @code{SIGHUP}, @code{SIGQUIT}, @code{SIGINT}, @code{SIGUSR1} and
+@code{SIGUSR2}. Shortened names without @samp{SIG} prefix are also
+accepted.
+@end table
+Both forms of @option{--totals} option can be used simultaneously.
+Thus, @kbd{tar -x --totals --totals=USR1} instructs @command{tar} to
+extract all members from its default archive and print statistics
+after finishing the extraction, as well as when receiving signal
+@code{SIGUSR1}.
+
+@anchor{Progress information}
@cindex Progress information
@opindex checkpoint
The @option{--checkpoint} option prints an occasional message
-as @command{tar} reads or writes the archive. In fact, it prints
-a message each 10 records read or written. It is designed for
+as @command{tar} reads or writes the archive. It is designed for
those who don't need the more detailed (and voluminous) output of
@option{--block-number} (@option{-R}), but do want visual confirmation
-that @command{tar} is actually making forward progress.
+that @command{tar} is actually making forward progress. By default it
+prints a message each 10 records read or written. This can be changed
+by giving it a numeric argument after an equal sign:
+
+@smallexample
+$ @kbd{tar -c --checkpoint=1000} /var
+tar: Write checkpoint 1000
+tar: Write checkpoint 2000
+tar: Write checkpoint 3000
+@end smallexample
-@FIXME{There is some confusion here. It seems that -R once wrote a
-message at @samp{every} record read or written.}
+This example shows the default checkpoint message used by
+@command{tar}. If you place a dot immediately after the equal
+sign, it will print a @samp{.} at each checkpoint. For example:
+
+@smallexample
+$ @kbd{tar -c --checkpoint=.1000} /var
+...
+@end smallexample
@opindex show-omitted-dirs
@anchor{show-omitted-dirs}
to be printed for each directory in the archive which is skipped.
This happens regardless of the reason for skipping: the directory might
not have been named on the command line (implicitly or explicitly),
-it might be excluded by the use of the @option{--exclude=@var{pattern}} option, or
-some other reason.
+it might be excluded by the use of the
+@option{--exclude=@var{pattern}} option, or some other reason.
@opindex block-number
@cindex Block number where error occurred
for these operations.
@table @option
-@opindex create, complementary notes
+@xopindex{create, complementary notes}
@item --create
@itemx -c
@kbd{tar cfT empty-archive.tar /dev/null}
@end smallexample
-@opindex extract, complementary notes
+@xopindex{extract, complementary notes}
@item --extract
@itemx --get
@itemx -x
ready. In the meantime, programs not being localizable for dates
should prefer international dates, that's really the way to go.
-Look up @url{http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html} if you
+Look up @url{http://www.cl.cam.ac.uk/@/~mgk25/@/iso-time.html} if you
are curious, it contains a detailed explanation of the ISO 8601 standard.
@end table
@samp{collection.tar} and @samp{music.tar}.
We will also use the archive files @samp{afiles.tar} and
-@samp{bfiles.tar}. @samp{afiles.tar} contains the members @samp{apple},
-@samp{angst}, and @samp{aspic}. @samp{bfiles.tar} contains the members
+@samp{bfiles.tar}. The archive @samp{afiles.tar} contains the members @samp{apple},
+@samp{angst}, and @samp{aspic}; @samp{bfiles.tar} contains the members
@samp{./birds}, @samp{baboon}, and @samp{./box}.
Unless we state otherwise, all practicing you do and examples you follow
@end smallexample
@node multiple
-@subsubsection Multiple Files with the Same Name
+@subsubsection Multiple Members with the Same Name
You can use @option{--append} (@option{-r}) to add copies of files
which have been updated since the archive was created. (However, we
Both @option{--update} and @option{--append} work by adding to the end
of the archive. When you extract a file from the archive, only the
version stored last will wind up in the file system, unless you use
-the @option{--backup} option. @FIXME-ref{Multiple Members with the
-Same Name}
+the @option{--backup} option. @xref{multiple}, for a detailed discussion.
@menu
* how to update::
@option{--file} option and name the rest of archives to be
concatenated on the command line. The members, and their member
names, will be copied verbatim from those archives to the first one.
-@FIXME-ref{This can cause multiple members to have the same name, for
-information on how this affects reading the archive, Multiple
-Members with the Same Name.}
+@footnote{This can cause multiple members to have the same name, for
+information on how this affects reading the archive, @ref{multiple}.}
The new, concatenated archive will be called by the same name as the
one given with the @option{--file} option. As usual, if you omit
@option{--file}, @command{tar} will use the value of the environment
@node create options
@section Options Used by @option{--create}
-@opindex create, additional options
+@xopindex{create, additional options}
The previous chapter described the basics of how to use
@option{--create} (@option{-c}) to create an archive from a set of files.
@xref{create}. This section described advanced options to be used with
@option{--create}.
@menu
+* override:: Overriding File Metadata.
* Ignore Failed Read::
@end menu
-@node Ignore Failed Read
-@subsection Ignore Fail Read
+@node override
+@subsection Overriding File Metadata
+
+As described above, a @command{tar} archive keeps, for each member it contains,
+its @dfn{metadata}, such as modification time, mode and ownership of
+the file. @GNUTAR{} allows to replace these data with other values
+when adding files to the archive. The options described in this
+section affect creation of archives of any type. For POSIX archives,
+see also @ref{PAX keywords}, for additional ways of controlling
+metadata, stored in the archive.
+
+@table @option
+@opindex mode
+@item --mode=@var{permissions}
+
+When adding files to an archive, @command{tar} will use
+@var{permissions} for the archive members, rather than the permissions
+from the files. @var{permissions} can be specified either as an octal
+number or as symbolic permissions, like with
+@command{chmod} (@xref{File permissions, Permissions, File
+permissions, fileutils, @acronym{GNU} file utilities}. This reference
+also has useful information for those not being overly familiar with
+the UNIX permission system). Using latter syntax allows for
+more flexibility. For example, the value @samp{a+rw} adds read and write
+permissions for everybody, while retaining executable bits on directories
+or on any other file already marked as executable:
+
+@smallexample
+$ @kbd{tar -c -f archive.tar --mode='a+rw' .}
+@end smallexample
+
+@item --mtime=@var{date}
+@opindex mtime
+
+When adding files to an archive, @command{tar} will use @var{date} as
+the modification time of members when creating archives, instead of
+their actual modification times. The argument @var{date} can be
+either a textual date representation in almost arbitrary format
+(@pxref{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 will be used.
+
+The following example will set the modification date to 00:00:00 UTC,
+January 1, 1970:
+
+@smallexample
+$ @kbd{tar -c -f archive.tar --mtime='1970-01-01' .}
+@end smallexample
+
+@noindent
+When used with @option{--verbose} (@pxref{verbose tutorial}) @GNUTAR{}
+will try to convert the specified date back to its textual
+representation and compare it with the one given with
+@option{--mtime} options. If the two dates differ, @command{tar} will
+print a warning saying what date it will use. This is to help user
+ensure he is using the right date.
+
+For example:
+
+@smallexample
+$ @kbd{tar -c -f archive.tar -v --mtime=yesterday .}
+tar: Option --mtime: Treating date `yesterday' as 2006-06-20
+13:06:29.152478
+@dots{}
+@end smallexample
+
+@item --owner=@var{user}
+@opindex owner
+
+Specifies that @command{tar} should use @var{user} as the owner of members
+when creating archives, instead of the user associated with the source
+file. The argument @var{user} can be either an existing user symbolic
+name, or a decimal numeric user ID.
+
+There is no value indicating a missing number, and @samp{0} usually means
+@code{root}. Some people like to force @samp{0} as the value to offer in
+their distributions for the owner of files, because the @code{root} user is
+anonymous anyway, so that might as well be the owner of anonymous
+archives. For example:
+
+@smallexample
+@group
+$ @kbd{tar -c -f archive.tar --owner=0 .}
+# @r{Or:}
+$ @kbd{tar -c -f archive.tar --owner=root .}
+@end group
+@end smallexample
+
+@item --group=@var{group}
+@opindex group
+
+Files added to the @command{tar} archive will have a group id of @var{group},
+rather than the group from the source file. The argument @var{group}
+can be either an existing group symbolic name, or a decimal numeric group ID.
+@end table
+
+@node Ignore Failed Read
+@subsection Ignore Fail Read
@table @option
@item --ignore-failed-read
+@opindex ignore-failed-read
Do not exit with nonzero on unreadable files or directories.
@end table
@section Options Used by @option{--extract}
@UNREVISED
-@opindex extract, additional options
+@xopindex{extract, additional options}
The previous chapter showed how to use @option{--extract} to extract
an archive into the file system. Various options cause @command{tar} to
extract more information than just file contents, such as the owner,
@node Dealing with Old Files
@unnumberedsubsubsec Options Controlling the Overwriting of Existing Files
-@opindex overwrite-dir, introduced
+@xopindex{overwrite-dir, introduced}
When extracting files, if @command{tar} discovers that the extracted
file already exists, it normally replaces the file by removing it before
extracting it, to prevent confusion in the presence of hard or symbolic
such a directory, use the @option{--no-overwrite-dir} option.
@cindex Overwriting old files, prevention
-@opindex keep-old-files, introduced
+@xopindex{keep-old-files, introduced}
To be even more cautious and prevent existing files from being replaced, use
the @option{--keep-old-files} (@option{-k}) option. It causes @command{tar} to refuse
to replace or update a file that already exists, i.e., a file with the
same name as an archive member prevents extraction of that archive
member. Instead, it reports an error.
-@opindex overwrite, introduced
+@xopindex{overwrite, introduced}
To be more aggressive about altering existing files, use the
@option{--overwrite} option. It causes @command{tar} to overwrite
existing files and to follow existing symbolic links when extracting.
to allow this behavior. In any case, single files are silently
removed.
-@opindex unlink-first, introduced
+@xopindex{unlink-first, introduced}
Finally, the @option{--unlink-first} (@option{-U}) option can improve performance in
some cases by causing @command{tar} to remove files unconditionally
before extracting them.
@option{-x}) operation.
@table @option
-@opindex preserve-permission
-@opindex same-permission
-@item --preserve-permission
-@itemx --same-permission
+@opindex preserve-permissions
+@opindex same-permissions
+@item --preserve-permissions
+@itemx --same-permissions
@c @itemx --ignore-umask
@itemx -p
Set modes of extracted archive members to those recorded in the
@end table
-Some people express the desire to @emph{always} use the @option{--backup}
-option, by defining some kind of alias or script. This is not as easy
-as one may think, due to the fact that old style options should appear first
-and consume arguments a bit unpredictably for an alias or script. But,
-if you are ready to give up using old style options, you may resort to
-using something like (a Bourne shell function here):
-
-@smallexample
-tar () @{ /usr/local/bin/tar --backup $*; @}
-@end smallexample
-
@node Applications
@section Notable @command{tar} Usages
@UNREVISED
Note that incremental archives use @command{tar} extensions and may
not be readable by non-@acronym{GNU} versions of the @command{tar} program.
-@opindex listed-incremental, using with @option{--extract}
-@opindex extract, using with @option{--listed-incremental}
+@xopindex{listed-incremental, using with @option{--extract}}
+@xopindex{extract, using with @option{--listed-incremental}}
To extract from the incremental dumps, use
@option{--listed-incremental} together with @option{--extract}
option (@pxref{extracting files}). In this case, @command{tar} does
verbose listing output (@option{--list --verbose}) when using in
scripts.
-@opindex incremental, using with @option{--list}
-@opindex listed-incremental, using with @option{--list}
-@opindex list, using with @option{--incremental}
-@opindex list, using with @option{--listed-incremental}
+@xopindex{incremental, using with @option{--list}}
+@xopindex{listed-incremental, using with @option{--list}}
+@xopindex{list, using with @option{--incremental}}
+@xopindex{list, using with @option{--listed-incremental}}
Versions of @GNUTAR{} up to 1.15.1 used to dump verbatim binary
contents of the DUMPDIR header (with terminating nulls) when
@option{--incremental} or @option{--listed-incremental} option was
the host machine must have @GNUTAR{} installed, and
must be able to access the directory containing the backup scripts and
their support files using the same file name that is used on the
-machine where the scripts are run (ie. what @command{pwd} will print
+machine where the scripts are run (i.e. what @command{pwd} will print
when in that directory on that machine). If the host that contains
the file system does not have this capability, you can specify another
host as long as it can access the file system through NFS.
Script to be run when it's time to insert a new tape in for the next
volume. Administrators may want to tailor this script for their site.
-If this variable isn't set, @GNUTAR{} will display its built-in prompt
-@FIXME-xref{describe it somewhere!}, and will expect confirmation from
-the console.
+If this variable isn't set, @GNUTAR{} will display its built-in
+prompt, and will expect confirmation from the console. For the
+description of the default prompt, see @ref{change volume prompt}.
+
@end defvr
@defvr {Backup variable} SLEEP_MESSAGE
volumes as they are needed. If the archive is on tape, you don't need
to rewind the tape to to its beginning---if the tape head is
positioned past the beginning of the archive, the script will rewind
-the tape as needed. @FIXME-xref{Media, for a discussion of tape
-positioning.}
+the tape as needed. @xref{Tape Positioning}, for a discussion of tape
+positioning.
@quotation
@strong{Warning:} The script will delete files from the active file
instead of the default archive file location.
@table @option
-@opindex file, short description
+@xopindex{file, short description}
@item --file=@var{archive-name}
@itemx -f @var{archive-name}
Name the archive to create or operate on. Use in conjunction with
If you do not name the archive, @command{tar} uses the value of the
environment variable @env{TAPE} as the file name for the archive. If
that is not available, @command{tar} uses a default, compiled-in archive
-name, usually that for tape unit zero (ie. @file{/dev/tu00}).
+name, usually that for tape unit zero (i.e. @file{/dev/tu00}).
@cindex Standard input and output
@cindex tar to standard input and output
@option{--add-file} option to prevent it from being treated as an
option.
+@anchor{input name quoting}
+By default @GNUTAR{} attempts to @dfn{unquote} each file or member
+name, replacing @dfn{escape sequences} according to the following
+table:
+
+@multitable @columnfractions 0.20 0.60
+@headitem Escape @tab Replaced with
+@item \a @tab Audible bell (ASCII 7)
+@item \b @tab Backspace (ASCII 8)
+@item \f @tab Form feed (ASCII 12)
+@item \n @tab New line (ASCII 10)
+@item \r @tab Carriage return (ASCII 13)
+@item \t @tab Horizontal tabulation (ASCII 9)
+@item \v @tab Vertical tabulation (ASCII 11)
+@item \? @tab ASCII 127
+@item \@var{n} @tab ASCII @var{n} (@var{n} should be an octal number
+ of up to 3 digits)
+@end multitable
+
+A backslash followed by any other symbol is retained.
+
+This default behavior is controlled by the following command line
+option:
+
+@table @option
+@opindex unquote
+@item --unquote
+Enable unquoting input file or member names (default).
+
+@opindex no-unquote
+@item --no-unquote
+Disable unquoting input file or member names.
+@end table
+
If you specify a directory name as a file name argument, all the files
in that directory are operated on by @command{tar}.
@end smallexample
@noindent
-@opindex directory, using in @option{--files-from} argument
+@xopindex{directory, using in @option{--files-from} argument}
Notice that the option parsing algorithm used with @option{-T} is
stricter than the one used by shell. Namely, when specifying option
arguments, you should observe the following rules:
@node problems with exclude
@unnumberedsubsec Problems with Using the @code{exclude} Options
-@opindex exclude, potential problems with
+@xopindex{exclude, potential problems with}
Some users find @samp{exclude} options confusing. Here are some common
pitfalls:
literally @footnote{Notice that earlier @GNUTAR{} versions used
globbing for inclusion members, which contradicted to UNIX98
specification and was not documented. @xref{Changes}, for more
-information on this and other changes} and exclusion members are
+information on this and other changes.} and exclusion members are
treated as globbing patterns. For example:
@smallexample
--ignore-case --exclude='makefile' --no-ignore-case ---exclude='readme'
@end smallexample
+@noindent
ignores case when excluding @samp{makefile}, but not when excluding
@samp{readme}.
absolute file names or those that begin with a @file{../}. @GNUTAR{}
takes special precautions when extracting such names and provides a
special option for handling them, which is described in
-@xref{absolute}.
+@ref{absolute}.
Secondly, you may wish to extract file names without some leading
directory components, or with otherwise modified names. In other
@anchor{show-transformed-names}
@table @option
-@opindex --show-transformed-names
+@opindex show-transformed-names
@item --show-transformed-names
Display file or member names with all requested transformations
applied.
@end table
+@noindent
For example:
@smallexample
@GNUTAR{} provides a general-purpose transformation option:
@table @option
-@opindex --transform
+@opindex transform
@item --transform=@var{expression}
Modify file names using supplied @var{expression}.
@end table
@item x
@var{regexp} is an @dfn{extended regular expression} (@pxref{Extended
regexps, Extended regular expressions, Extended regular expressions,
-sed, GNU sed}.
+sed, GNU sed}).
@item @var{number}
Only replace the @var{number}th match of the @var{regexp}.
@end group
@end smallexample
-Changing of delimiter is often useful when the @var{regex} contains
-slashes. For example, it is more convenient to write:
-
-@smallexample
-s,/,-,
-@end smallexample
-
-@noindent
-instead of
-
-@smallexample
-s/\//-/
-@end smallexample
+Changing delimiters is often useful when the @var{regex} contains
+slashes. For example, it is more convenient to write @code{s,/,-,} than
+@code{s/\//-/}.
Here are several examples of @option{--transform} usage:
$ @kbd{tar -cf arch.tar --transform='s,^usr/,var/,' /}
@end smallexample
-To test @option{--transform} effect we suggest to use
-@option{--show-transformed-names}:
+To test @option{--transform} effect we suggest using
+@option{--show-transformed-names} option:
@smallexample
$ @kbd{tar -cf arch.tar --transform='s,^usr/,var/,' \
$ @kbd{tar -cf foo.tar --newer-mtime '2 days ago'}
@end smallexample
+When any of these options is used with the option @option{--verbose}
+(@pxref{verbose tutorial}) @GNUTAR{} will try to convert the specified
+date back to its textual representation and compare that with the
+one given with the option. If the two dates differ, @command{tar} will
+print a warning saying what date it will use. This is to help user
+ensure he is using the right date. For example:
+
+@smallexample
+@group
+$ @kbd{tar -c -f archive.tar --after-date='10 days ago' .}
+tar: Option --after-date: Treating date `10 days ago' as 2006-06-11
+13:19:37.232434
+@end group
+@end smallexample
+
@quotation
@strong{Please Note:} @option{--after-date} and @option{--newer-mtime}
should not be used for incremental backups. @xref{Incremental Dumps},
* Portability:: Making @command{tar} Archives More Portable
* Compression:: Using Less Space through Compression
* Attributes:: Handling File Attributes
-* Standard:: The Standard Format
-* Extensions:: @acronym{GNU} Extensions to the Archive Format
* cpio:: Comparison of @command{tar} and @command{cpio}
@end menu
@cindex POSIX archive format
@cindex PAX archive format
-The version @value{VERSION} of @GNUTAR{} is able
-to read and create archives conforming to @acronym{POSIX.1-2001} standard.
+Starting from version 1.14 @GNUTAR{} features full support for
+@acronym{POSIX.1-2001} archives.
A @acronym{POSIX} conformant archive will be created if @command{tar}
-was given @option{--format=posix} option.
+was given @option{--format=posix} (@option{--format=pax}) option. No
+special option is required to read and extract from a @acronym{POSIX}
+archive.
+
+@menu
+* PAX keywords:: Controlling Extended Header Keywords.
+@end menu
+
+@node PAX keywords
+@subsubsection Controlling Extended Header Keywords
+
+@table @option
+@opindex pax-option
+@item --pax-option=@var{keyword-list}
+Handle keywords in @acronym{PAX} extended headers. This option is
+equivalent to @option{-o} option of the @command{pax} utility.
+@end table
+
+@var{Keyword-list} is a comma-separated
+list of keyword options, each keyword option taking one of
+the following forms:
+
+@table @code
+@item delete=@var{pattern}
+When used with one of archive-creation commands,
+this option instructs @command{tar} to omit from extended header records
+that it produces any keywords matching the string @var{pattern}.
+
+When used in extract or list mode, this option instructs tar
+to ignore any keywords matching the given @var{pattern} in the extended
+header records. In both cases, matching is performed using the pattern
+matching notation described in @acronym{POSIX 1003.2}, 3.13
+(@pxref{wildcards}). For example:
+
+@smallexample
+--pax-option delete=security.*
+@end smallexample
+
+would suppress security-related information.
+
+@item exthdr.name=@var{string}
+
+This keyword allows user control over the name that is written into the
+ustar header blocks for the extended headers. The name is obtained
+from @var{string} after making the following substitutions:
+
+@multitable @columnfractions .25 .55
+@headitem Meta-character @tab Replaced By
+@item %d @tab The directory name of the file, equivalent to the
+result of the @command{dirname} utility on the translated pathname.
+@item %f @tab The filename of the file, equivalent to the result
+of the @command{basename} utility on the translated pathname.
+@item %p @tab The process ID of the @command{tar} process.
+@item %% @tab A @samp{%} character.
+@end multitable
+
+Any other @samp{%} characters in @var{string} produce undefined
+results.
+
+If no option @samp{exthdr.name=string} is specified, @command{tar}
+will use the following default value:
+
+@smallexample
+%d/PaxHeaders.%p/%f
+@end smallexample
+
+@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
+is obtained from the contents of @var{string}, after making
+the following substitutions:
+
+@multitable @columnfractions .25 .55
+@headitem Meta-character @tab Replaced By
+@item %n @tab An integer that represents the
+sequence number of the global extended header record in the archive,
+starting at 1.
+@item %p @tab The process ID of the @command{tar} process.
+@item %% @tab A @samp{%} character.
+@end multitable
+
+Any other @samp{%} characters in @var{string} produce undefined results.
+
+If no option @samp{globexthdr.name=string} is specified, @command{tar}
+will use the following default value:
+
+@smallexample
+$TMPDIR/GlobalHead.%p.%n
+@end smallexample
+
+@noindent
+where @samp{$TMPDIR} represents the value of the @var{TMPDIR}
+environment variable. If @var{TMPDIR} is not set, @command{tar}
+uses @samp{/tmp}.
+
+@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
+header record. When used with one of archive-reading commands,
+@command{tar} will behave as if it has encountered these keyword/value
+pairs at the beginning of the archive in a global extended header
+record.
+
+@item @var{keyword}:=@var{value}
+When used with one of archive-creation commands, these keyword/value pairs
+will be included as records at the beginning of an extended header for
+each file. This is effectively equivalent to @var{keyword}=@var{value}
+form except that it creates no global extended header records.
+
+When used with one of archive-reading commands, @command{tar} will
+behave as if these keyword/value pairs were included as records at the
+end of each extended header; thus, they will override any global or
+file-specific extended header record keywords of the same names.
+For example, in the command:
+
+@smallexample
+tar --format=posix --create \
+ --file archive --pax-option gname:=user .
+@end smallexample
+
+the group name will be forced to a new value for all files
+stored in the archive.
+@end table
@node Checksumming
@subsection Checksumming Problems
implement your own filters, not necessarily dealing with
compression/decomression. For example, suppose you wish to implement
PGP encryption on top of compression, using @command{gpg} (@pxref{Top,
-gpg, gpg ---- encryption and signing tool, gpg}). The following
-script does that:
+gpg, gpg ---- encryption and signing tool, gpg, GNU Privacy Guard
+Manual}). The following script does that:
@smallexample
@group
@acronym{GNU} options. For now, it is an option needing to be specified on
the command line with the creation or updating of an archive.
-Files in the file system occasionally have ``holes.'' A hole in a file
+Files in the file system occasionally have @dfn{holes}. A @dfn{hole} in a file
is a section of the file's contents which was never written. The
contents of a hole read as all zeros. On many operating systems,
actual disk storage is not allocated for holes, but they are counted
already crowded with options and moreover, the approach just explained
gives you a great deal of control already.
-@opindex same-permissions, short description
-@opindex preserve-permissions, short description
+@xopindex{same-permissions, short description}
+@xopindex{preserve-permissions, short description}
@item -p
@itemx --same-permissions
@itemx --preserve-permissions
@end table
-@node Standard
-@section Basic Tar Format
-@UNREVISED
-
-While an archive may contain many files, the archive itself is a
-single ordinary file. Like any other file, an archive file can be
-written to a storage device such as a tape or disk, sent through a
-pipe or over a network, saved on the active file system, or even
-stored in another archive. An archive file is not easy to read or
-manipulate without using the @command{tar} utility or Tar mode in
-@acronym{GNU} Emacs.
-
-Physically, an archive consists of a series of file entries terminated
-by an end-of-archive entry, which consists of two 512 blocks of zero
-bytes. A file
-entry usually describes one of the files in the archive (an
-@dfn{archive member}), and consists of a file header and the contents
-of the file. File headers contain file names and statistics, checksum
-information which @command{tar} uses to detect file corruption, and
-information about file types.
-
-Archives are permitted to have more than one member with the same
-member name. One way this situation can occur is if more than one
-version of a file has been stored in the archive. For information
-about adding new versions of a file to an archive, see @ref{update}.
-@FIXME-xref{To learn more about having more than one archive member with the
-same name, see -backup node, when it's written.}
-
-In addition to entries describing archive members, an archive may
-contain entries which @command{tar} itself uses to store information.
-@xref{label}, for an example of such an archive entry.
-
-A @command{tar} archive file contains a series of blocks. Each block
-contains @code{BLOCKSIZE} bytes. Although this format may be thought
-of as being on magnetic tape, other media are often used.
-
-Each file archived is represented by a header block which describes
-the file, followed by zero or more blocks which give the contents
-of the file. At the end of the archive file there are two 512-byte blocks
-filled with binary zeros as an end-of-file marker. A reasonable system
-should write such end-of-file marker at the end of an archive, but
-must not assume that such a block exists when reading an archive. In
-particular @GNUTAR{} always issues a warning if it does not encounter it.
-
-The blocks may be @dfn{blocked} for physical I/O operations.
-Each record of @var{n} blocks (where @var{n} is set by the
-@option{--blocking-factor=@var{512-size}} (@option{-b @var{512-size}}) option to @command{tar}) is written with a single
-@w{@samp{write ()}} operation. On magnetic tapes, the result of
-such a write is a single record. When writing an archive,
-the last record of blocks should be written at the full size, with
-blocks after the zero block containing all zeros. When reading
-an archive, a reasonable system should properly handle an archive
-whose last record is shorter than the rest, or which contains garbage
-records after a zero block.
-
-The header block is defined in C as follows. In the @GNUTAR{}
-distribution, this is part of file @file{src/tar.h}:
-
-@smallexample
-@include header.texi
-@end smallexample
-
-All characters in header blocks are represented by using 8-bit
-characters in the local variant of ASCII. Each field within the
-structure is contiguous; that is, there is no padding used within
-the structure. Each character on the archive medium is stored
-contiguously.
-
-Bytes representing the contents of files (after the header block
-of each file) are not translated in any way and are not constrained
-to represent characters in any character set. The @command{tar} format
-does not distinguish text files from binary files, and no translation
-of file contents is performed.
-
-The @code{name}, @code{linkname}, @code{magic}, @code{uname}, and
-@code{gname} are null-terminated character strings. All other fields
-are zero-filled octal numbers in ASCII. Each numeric field of width
-@var{w} contains @var{w} minus 1 digits, and a null.
-
-The @code{name} field is the file name of the file, with directory names
-(if any) preceding the file name, separated by slashes.
-
-@FIXME{how big a name before field overflows?}
-
-The @code{mode} field provides nine bits specifying file permissions
-and three bits to specify the Set UID, Set GID, and Save Text
-(@dfn{sticky}) modes. Values for these bits are defined above.
-When special permissions are required to create a file with a given
-mode, and the user restoring files from the archive does not hold such
-permissions, the mode bit(s) specifying those special permissions
-are ignored. Modes which are not supported by the operating system
-restoring files from the archive will be ignored. Unsupported modes
-should be faked up when creating or updating an archive; e.g., the
-group permission could be copied from the @emph{other} permission.
-
-The @code{uid} and @code{gid} fields are the numeric user and group
-ID of the file owners, respectively. If the operating system does
-not support numeric user or group IDs, these fields should be ignored.
-
-The @code{size} field is the size of the file in bytes; linked files
-are archived with this field specified as zero. @FIXME-xref{Modifiers, in
-particular the @option{--incremental} (@option{-G}) option.}
-
-The @code{mtime} field is the data modification time of the file at
-the time it was archived. It is the ASCII representation of the octal
-value of the last time the file's contents were modified, represented
-as an integer number of
-seconds since January 1, 1970, 00:00 Coordinated Universal Time.
-
-The @code{chksum} field is the ASCII representation of the octal value
-of the simple sum of all bytes in the header block. Each 8-bit
-byte in the header is added to an unsigned integer, initialized to
-zero, the precision of which shall be no less than seventeen bits.
-When calculating the checksum, the @code{chksum} field is treated as
-if it were all blanks.
-
-The @code{typeflag} field specifies the type of file archived. If a
-particular implementation does not recognize or permit the specified
-type, the file will be extracted as if it were a regular file. As this
-action occurs, @command{tar} issues a warning to the standard error.
-
-The @code{atime} and @code{ctime} fields are used in making incremental
-backups; they store, respectively, the particular file's access and
-status change times.
-
-The @code{offset} is used by the @option{--multi-volume} (@option{-M}) option, when
-making a multi-volume archive. The offset is number of bytes into
-the file that we need to restart at to continue the file on the next
-tape, i.e., where we store the location that a continued file is
-continued at.
-
-The following fields were added to deal with sparse files. A file
-is @dfn{sparse} if it takes in unallocated blocks which end up being
-represented as zeros, i.e., no useful data. A test to see if a file
-is sparse is to look at the number blocks allocated for it versus the
-number of characters in the file; if there are fewer blocks allocated
-for the file than would normally be allocated for a file of that
-size, then the file is sparse. This is the method @command{tar} uses to
-detect a sparse file, and once such a file is detected, it is treated
-differently from non-sparse files.
-
-Sparse files are often @code{dbm} files, or other database-type files
-which have data at some points and emptiness in the greater part of
-the file. Such files can appear to be very large when an @samp{ls
--l} is done on them, when in truth, there may be a very small amount
-of important data contained in the file. It is thus undesirable
-to have @command{tar} think that it must back up this entire file, as
-great quantities of room are wasted on empty blocks, which can lead
-to running out of room on a tape far earlier than is necessary.
-Thus, sparse files are dealt with so that these empty blocks are
-not written to the tape. Instead, what is written to the tape is a
-description, of sorts, of the sparse file: where the holes are, how
-big the holes are, and how much data is found at the end of the hole.
-This way, the file takes up potentially far less room on the tape,
-and when the file is extracted later on, it will look exactly the way
-it looked beforehand. The following is a description of the fields
-used to handle a sparse file:
-
-The @code{sp} is an array of @code{struct sparse}. Each @code{struct
-sparse} contains two 12-character strings which represent an offset
-into the file and a number of bytes to be written at that offset.
-The offset is absolute, and not relative to the offset in preceding
-array element.
-
-The header can hold four of these @code{struct sparse} at the moment;
-if more are needed, they are not stored in the header.
-
-The @code{isextended} flag is set when an @code{extended_header}
-is needed to deal with a file. Note that this means that this flag
-can only be set when dealing with a sparse file, and it is only set
-in the event that the description of the file will not fit in the
-allotted room for sparse structures in the header. In other words,
-an extended_header is needed.
-
-The @code{extended_header} structure is used for sparse files which
-need more sparse structures than can fit in the header. The header can
-fit 4 such structures; if more are needed, the flag @code{isextended}
-gets set and the next block is an @code{extended_header}.
-
-Each @code{extended_header} structure contains an array of 21
-sparse structures, along with a similar @code{isextended} flag
-that the header had. There can be an indeterminate number of such
-@code{extended_header}s to describe a sparse file.
-
-@table @asis
-
-@item @code{REGTYPE}
-@itemx @code{AREGTYPE}
-These flags represent a regular file. In order to be compatible
-with older versions of @command{tar}, a @code{typeflag} value of
-@code{AREGTYPE} should be silently recognized as a regular file.
-New archives should be created using @code{REGTYPE}. Also, for
-backward compatibility, @command{tar} treats a regular file whose name
-ends with a slash as a directory.
-
-@item @code{LNKTYPE}
-This flag represents a file linked to another file, of any type,
-previously archived. Such files are identified in Unix by each
-file having the same device and inode number. The linked-to name is
-specified in the @code{linkname} field with a trailing null.
-
-@item @code{SYMTYPE}
-This represents a symbolic link to another file. The linked-to name
-is specified in the @code{linkname} field with a trailing null.
-
-@item @code{CHRTYPE}
-@itemx @code{BLKTYPE}
-These represent character special files and block special files
-respectively. In this case the @code{devmajor} and @code{devminor}
-fields will contain the major and minor device numbers respectively.
-Operating systems may map the device specifications to their own
-local specification, or may ignore the entry.
-
-@item @code{DIRTYPE}
-This flag specifies a directory or sub-directory. The directory
-name in the @code{name} field should end with a slash. On systems where
-disk allocation is performed on a directory basis, the @code{size} field
-will contain the maximum number of bytes (which may be rounded to
-the nearest disk block allocation unit) which the directory may
-hold. A @code{size} field of zero indicates no such limiting. Systems
-which do not support limiting in this manner should ignore the
-@code{size} field.
-
-@item @code{FIFOTYPE}
-This specifies a FIFO special file. Note that the archiving of a
-FIFO file archives the existence of this file and not its contents.
-
-@item @code{CONTTYPE}
-This specifies a contiguous file, which is the same as a normal
-file except that, in operating systems which support it, all its
-space is allocated contiguously on the disk. Operating systems
-which do not allow contiguous allocation should silently treat this
-type as a normal file.
-
-@item @code{A} @dots{} @code{Z}
-These are reserved for custom implementations. Some of these are
-used in the @acronym{GNU} modified format, as described below.
-
-@end table
-
-Other values are reserved for specification in future revisions of
-the P1003 standard, and should not be used by any @command{tar} program.
-
-The @code{magic} field indicates that this archive was output in
-the P1003 archive format. If this field contains @code{TMAGIC},
-the @code{uname} and @code{gname} fields will contain the ASCII
-representation of the owner and group of the file respectively.
-If found, the user and group IDs are used rather than the values in
-the @code{uid} and @code{gid} fields.
-
-For references, see ISO/IEC 9945-1:1990 or IEEE Std 1003.1-1990, pages
-169-173 (section 10.1) for @cite{Archive/Interchange File Format}; and
-IEEE Std 1003.2-1992, pages 380-388 (section 4.48) and pages 936-940
-(section E.4.48) for @cite{pax - Portable archive interchange}.
-
-@node Extensions
-@section @acronym{GNU} Extensions to the Archive Format
-@UNREVISED
-
-The @acronym{GNU} format uses additional file types to describe new types of
-files in an archive. These are listed below.
-
-@table @code
-@item GNUTYPE_DUMPDIR
-@itemx 'D'
-This represents a directory and a list of files created by the
-@option{--incremental} (@option{-G}) option. The @code{size} field gives the total
-size of the associated list of files. Each file name is preceded by
-either a @samp{Y} (the file should be in this archive) or an @samp{N}.
-(The file is a directory, or is not stored in the archive.) Each file
-name is terminated by a null. There is an additional null after the
-last file name.
-
-@item GNUTYPE_MULTIVOL
-@itemx 'M'
-This represents a file continued from another volume of a multi-volume
-archive created with the @option{--multi-volume} (@option{-M}) option. The original
-type of the file is not given here. The @code{size} field gives the
-maximum size of this piece of the file (assuming the volume does
-not end before the file is written out). The @code{offset} field
-gives the offset from the beginning of the file where this part of
-the file begins. Thus @code{size} plus @code{offset} should equal
-the original size of the file.
-
-@item GNUTYPE_SPARSE
-@itemx 'S'
-This flag indicates that we are dealing with a sparse file. Note
-that archiving a sparse file requires special operations to find
-holes in the file, which mark the positions of these holes, along
-with the number of bytes of data to be found after the hole.
-
-@item GNUTYPE_VOLHDR
-@itemx 'V'
-This file type is used to mark the volume header that was given with
-the @option{--label=@var{archive-label}} (@option{-V @var{archive-label}}) option when the archive was created. The @code{name}
-field contains the @code{name} given after the @option{--label=@var{archive-label}} (@option{-V @var{archive-label}}) option.
-The @code{size} field is zero. Only the first file in each volume
-of an archive should have this type.
-
-@end table
-
-You may have trouble reading a @acronym{GNU} format archive on a
-non-@acronym{GNU} system if the options @option{--incremental} (@option{-G}),
-@option{--multi-volume} (@option{-M}), @option{--sparse} (@option{-S}), or @option{--label=@var{archive-label}} (@option{-V @var{archive-label}}) were
-used when writing the archive. In general, if @command{tar} does not
-use the @acronym{GNU}-added fields of the header, other versions of
-@command{tar} should be able to read the archive. Otherwise, the
-@command{tar} program will give an error, the most likely one being a
-checksum error.
-
@node cpio
@section Comparison of @command{tar} and @command{cpio}
@UNREVISED
@file{<sys/mtio.h>}.
@table @option
-@opindex force-local, short description
+@xopindex{force-local, short description}
@item --force-local
Archive file is local even if it contains a colon.
@item -[0-7][lmh]
Specify drive and density.
-@opindex multi-volume, short description
+@xopindex{multi-volume, short description}
@item -M
@itemx --multi-volume
Create/list/extract multi-volume archive.
that may be larger than will fit on the medium used to hold it.
@xref{Multi-Volume Archives}.
-@opindex tape-length, short description
+@xopindex{tape-length, short description}
@item -L @var{num}
@itemx --tape-length=@var{num}
Change tape after writing @var{num} x 1024 bytes.
detect end of physical tapes. By being slightly conservative on the
maximum tape length, you might avoid the problem entirely.
-@opindex info-script, short description
-@opindex new-volume-script, short description
+@xopindex{info-script, short description}
+@xopindex{new-volume-script, short description}
@item -F @var{file}
@itemx --info-script=@var{file}
@itemx --new-volume-script=@var{file}
@opindex blocking-factor
The data in an archive is grouped into blocks, which are 512 bytes.
Blocks are read and written in whole number multiples called
-@dfn{records}. The number of blocks in a record (ie. the size of a
+@dfn{records}. The number of blocks in a record (i.e. the size of a
record in units of 512 bytes) is called the @dfn{blocking factor}.
The @option{--blocking-factor=@var{512-size}} (@option{-b
@var{512-size}}) option specifies the blocking factor of an archive.
blocking factor (particularly if you're not sure what the blocking factor
is), you can usually use the @option{--read-full-records} (@option{-B}) option while
specifying a blocking factor larger then the blocking factor of the archive
-(ie. @samp{tar --extract --read-full-records --blocking-factor=300}.
+(i.e. @samp{tar --extract --read-full-records --blocking-factor=300}.
@xref{list}, for more information on the @option{--list} (@option{-t})
operation. @xref{Reading}, for a more detailed explanation of that option.
@command{tar} should rather drain the pipe out before exiting itself.
@end itemize
-@opindex ignore-zeros, short description
+@xopindex{ignore-zeros, short description}
@item -i
@itemx --ignore-zeros
Ignore blocks of zeros in archive (means EOF).
archive file, which may sometimes avoid problems when multiple files
are stored on a single physical tape.
-@opindex read-full-records, short description
+@xopindex{read-full-records, short description}
@item -B
@itemx --read-full-records
Reblock as we read (for reading 4.2BSD pipes).
@FIXME{Is there a better way to frob the spacing on the list?}
If you don't specify a @var{tapename}, @command{mt} uses the environment
-variable @env{TAPE}; if @env{TAPE} is not set, @command{mt} uses the device
-@file{/dev/rmt12}.
+variable @env{TAPE}; if @env{TAPE} is not set, @command{mt} will use
+the default device specified in your @file{sys/mtio.h} file
+(@code{DEFTAPE} variable). If this is not defined, the program will
+display a descriptive error message and exit with code 1.
@command{mt} returns a 0 exit status when the operation(s) were
successful, 1 if the command was unrecognized, and 2 if an operation
@node Using Multiple Tapes
@section Using Multiple Tapes
-@UNREVISED
Often you might want to write a large archive, one larger than will fit
on the actual tape you are using. In such a case, you can run multiple
@command{tar} commands, but this can be inconvenient, particularly if you
are using options like @option{--exclude=@var{pattern}} or dumping entire file systems.
-Therefore, @command{tar} supports multiple tapes automatically.
+Therefore, @command{tar} provides a special mode for creating
+multi-volume archives.
+
+@dfn{Multi-volume} archive is a single @command{tar} archive, stored
+on several media volumes of fixed size. Although in this section we will
+often call @samp{volume} a @dfn{tape}, there is absolutely no
+requirement for multi-volume archives to be stored on tapes. Instead,
+they can use whatever media type the user finds convenient, they can
+even be located on files.
+
+When creating a multi-volume arvhive, @GNUTAR{} continues to fill
+current volume until it runs out of space, then it switches to
+next volume (usually the operator is queried to replace the tape on
+this point), and continues working on the new volume. This operation
+continues untill all requested files are dumped. If @GNUTAR{} detects
+end of media while dumping a file, such a file is archived in split
+form. Some very big files can even be split across several volumes.
+
+Each volume is itself a valid @GNUTAR{} archive, so it can be read
+without any special options. Consequently any file member residing
+entirely on one volume can be extracted or otherwise operated upon
+without needing the other volume. Sure enough, to extract a split
+member you would need all volumes its parts reside on.
+
+Multi-volume archives suffer from several limitations. In particular,
+they cannot be compressed.
+
+@GNUTAR{} is able to create multi-volume archives of two formats
+(@pxref{Formats}): @samp{GNU} and @samp{POSIX}.
+
+@menu
+* Multi-Volume Archives:: Archives Longer than One Tape or Disk
+* Tape Files:: Tape Files
+* Tarcat:: Concatenate Volumes into a Single Archive
-Use @option{--multi-volume} (@option{-M}) on the command line, and
-then @command{tar} will, when it reaches the end of the tape, prompt
-for another tape, and continue the archive. Each tape will have an
-independent archive, and can be read without needing the other. (As
-an exception to this, the file that @command{tar} was archiving when
-it ran out of tape will usually be split between the two archives; in
-this case you need to extract from the first archive, using
-@option{--multi-volume}, and then put in the second tape when
-prompted, so @command{tar} can restore both halves of the file.)
+@end menu
-@GNUTAR{} multi-volume archives do not use a truly portable format.
-You need @GNUTAR{} at both ends to process them properly.
+@node Multi-Volume Archives
+@subsection Archives Longer than One Tape or Disk
+@cindex Multi-volume archives
+
+@opindex multi-volume
+To create an archive that is larger than will fit on a single unit of
+the media, use the @option{--multi-volume} (@option{-M}) option in conjunction with
+the @option{--create} option (@pxref{create}). A @dfn{multi-volume}
+archive can be manipulated like any other archive (provided the
+@option{--multi-volume} option is specified), but is stored on more
+than one tape or disk.
+
+When you specify @option{--multi-volume}, @command{tar} does not report an
+error when it comes to the end of an archive volume (when reading), or
+the end of the media (when writing). Instead, it prompts you to load
+a new storage volume. If the archive is on a magnetic tape, you
+should change tapes when you see the prompt; if the archive is on a
+floppy disk, you should change disks; etc.
+
+@table @option
+@item --multi-volume
+@itemx -M
+Creates a multi-volume archive, when used in conjunction with
+@option{--create} (@option{-c}). To perform any other operation on a multi-volume
+archive, specify @option{--multi-volume} in conjunction with that
+operation.
+For example:
+
+@smallexample
+$ @kbd{tar --create --multi-volume --file=/dev/tape @var{files}}
+@end smallexample
+@end table
+
+The method @command{tar} uses to detect end of tape is not perfect, and
+fails on some operating systems or on some devices. If @command{tar}
+cannot detect the end of the tape itself, you can use
+@option{--tape-length} option to inform it about the capacity of the
+tape:
+
+@anchor{tape-length}
+@table @option
+@opindex tape-length
+@item --tape-length=@var{size}
+@itemx -L @var{size}
+Set maximum length of a volume. The @var{size} argument should then
+be the usable size of the tape in units of 1024 bytes. This option
+selects @option{--multi-volume} automatically. For example:
+
+@smallexample
+$ @kbd{tar --create --tape-length=41943040 --file=/dev/tape @var{files}}
+@end smallexample
+@end table
+
+@anchor{change volume prompt}
+When @GNUTAR{} comes to the end of a storage media, it asks you to
+change the volume. The built-in prompt for POSIX locale
+is@footnote{If you run @GNUTAR{} under a different locale, the
+translation to the locale's language will be used.}:
+
+@smallexample
+Prepare volume #@var{n} for `@var{archive}' and hit return:
+@end smallexample
+
+@noindent
+where @var{n} is the ordinal number of the volume to be created and
+@var{archive} is archive file or device name.
When prompting for a new tape, @command{tar} accepts any of the following
responses:
Request @command{tar} to write the next volume on the file @var{file-name}.
@item !
Request @command{tar} to run a subshell. This option can be disabled
-by giving @option{--restrict} command line option to @command{tar}.
+by giving @option{--restrict} command line option to
+@command{tar}@footnote{@xref{--restrict}, for more information about
+this option}.
@item y
Request @command{tar} to begin writing the next volume.
@end table
(You should only type @samp{y} after you have changed the tape;
otherwise @command{tar} will write over the volume it just finished.)
+@cindex Volume number file
+@cindex volno file
+@anchor{volno-file}
+@opindex volno-file
+The volume number used by @command{tar} in its tape-changing prompt
+can be changed; if you give the
+@option{--volno-file=@var{file-of-number}} option, then
+@var{file-of-number} should be an unexisting file to be created, or
+else, a file already containing a decimal number. That number will be
+used as the volume number of the first volume written. When
+@command{tar} is finished, it will rewrite the file with the
+now-current volume number. (This does not change the volume number
+written on a tape label, as per @ref{label}, it @emph{only} affects
+the number used in the prompt.)
+
@cindex End-of-archive info script
@cindex Info script
@anchor{info-script}
@opindex info-script
@opindex new-volume-script
-If you want more elaborate behavior than this, give @command{tar} the
-@option{--info-script=@var{script-name}}
-(@option{--new-volume-script=@var{script-name}}, @option{-F
-@var{script-name}}) option. The file @var{script-name} is expected to
-be a program (or shell script) to be run instead of the normal
-prompting procedure. It is executed without any command line
-arguments. Additional data is passed to it via the following
+If you want more elaborate behavior than this, you can write a special
+@dfn{new volume script}, that will be responsible for changing the
+volume, and instruct @command{tar} to use it instead of its normal
+prompting procedure:
+
+@table @option
+@item --info-script=@var{script-name}
+@itemx --new-volume-script=@var{script-name}
+@itemx -F @var{script-name}
+Specify the full name of the volume script to use. The script can be
+used to eject cassettes, or to broadcast messages such as
+@samp{Someone please come change my tape} when performing unattended
+backups.
+@end table
+
+The @var{script-name} is executed without any command line
+arguments. It inherits @command{tar}'s shell environment.
+Additional data is passed to it via the following
environment variables:
@table @env
@vrindex TAR_SUBCOMMAND, info script environment variable
@item TAR_SUBCOMMAND
-Short option describing the operation @command{tar} is executed.
+Short option describing the operation @command{tar} is executing
@xref{Operations}, for a complete list of subcommand options.
@vrindex TAR_FORMAT, info script environment variable
list of archive format names.
@end table
-The info script can instruct @command{tar} to use new archive name,
-by writing in to file descriptor 3 (see below for an
-example).
+The volume script can instruct @command{tar} to use new archive name,
+by writing in to file descriptor 3 (see below for an example).
If the info script fails, @command{tar} exits; otherwise, it begins
writing the next volume.
-The method @command{tar} uses to detect end of tape is not perfect, and
-fails on some operating systems or on some devices. You can use the
-@option{--tape-length=@var{size}} (@option{-L @var{size}}) option if
-@command{tar} can't detect the end of the tape itself. This option
-selects @option{--multi-volume} (@option{-M}) automatically. The
-@var{size} argument should then be the usable size of the tape in
-units of 1024 bytes. But for many devices, and floppy disks in
-particular, this option is never required for real, as far as we know.
-
-@cindex Volume number file
-@cindex volno file
-@anchor{volno-file}
-@opindex volno-file
-The volume number used by @command{tar} in its tape-change prompt
-can be changed; if you give the
-@option{--volno-file=@var{file-of-number}} option, then
-@var{file-of-number} should be an unexisting file to be created, or
-else, a file already containing a decimal number. That number will be
-used as the volume number of the first volume written. When
-@command{tar} is finished, it will rewrite the file with the
-now-current volume number. (This does not change the volume number
-written on a tape label, as per @ref{label}, it @emph{only} affects
-the number used in the prompt.)
-
If you want @command{tar} to cycle through a series of files or tape
drives, there are three approaches to choose from. First of all, you
-can give @command{tar} multiple @option{--file} options. In this case
+can give @command{tar} multiple @option{--file} options. In this case
the specified files will be used, in sequence, as the successive
volumes of the archive. Only when the first one in the sequence needs
to be used again will @command{tar} prompt for a tape change (or run
-the info script). Secondly, you can use the @samp{n} response to the
-tape-change prompt, and, finally, you can use an info script, that
-writes new archive name to file descriptor. The following example
-illustrates this approach:
+the info script). For example, suppose someone has two tape drives on
+a system named @file{/dev/tape0} and @file{/dev/tape1}. For having
+@GNUTAR{} to switch to the second drive when it needs to write the
+second tape, and then back to the first tape, etc., just do either of:
+
+@smallexample
+$ @kbd{tar --create --multi-volume --file=/dev/tape0 --file=/dev/tape1 @var{files}}
+$ @kbd{tar cMff /dev/tape0 /dev/tape1 @var{files}}
+@end smallexample
+
+The second method is to use the @samp{n} response to the tape-change
+prompt.
+
+Finally, the most flexible approach is to use a volume script, that
+writes new archive name to the file descriptor #3. For example, the
+following volume script will create a series of archive files, named
+@file{@var{archive}-@var{vol}}, where @var{archive} is the name of the
+archive being created (as given by @option{--file} option) and
+@var{vol} is the ordinal number of the archive being created:
@smallexample
@group
@end group
@end smallexample
-Each volume of a multi-volume archive is an independent @command{tar}
-archive, complete in itself. For example, you can list or extract any
-volume alone; just don't specify @option{--multi-volume}
-(@option{-M}). However, if one file in the archive is split across
-volumes, the only way to extract it successfully is with a
-multi-volume extract command @option{--extract --multi-volume}
-(@option{-xM}) starting on or before the volume where the file begins.
-
-For example, let's presume someone has two tape drives on a system
-named @file{/dev/tape0} and @file{/dev/tape1}. For having @GNUTAR{}
-to switch to the second drive when it needs to write the
-second tape, and then back to the first tape, etc., just do either of:
+The same script cant be used while listing, comparing or extracting
+from the created archive. For example:
@smallexample
-$ @kbd{tar --create --multi-volume --file=/dev/tape0 --file=/dev/tape1 @var{files}}
-$ @kbd{tar cMff /dev/tape0 /dev/tape1 @var{files}}
+@group
+# @r{Create a multi-volume archive:}
+$ @kbd{tar -c -L1024 -f archive.tar -F new-volume .}
+# @r{Extract from the created archive:}
+$ @kbd{tar -x -f archive.tar -F new-volume .}
+@end group
@end smallexample
-@menu
-* Multi-Volume Archives:: Archives Longer than One Tape or Disk
-* Tape Files:: Tape Files
-* Tarcat:: Concatenate Volumes into a Single Archive
-
-@end menu
-
-@node Multi-Volume Archives
-@subsection Archives Longer than One Tape or Disk
-@cindex Multi-volume archives
-@UNREVISED
-
-@opindex multi-volume
-To create an archive that is larger than will fit on a single unit of
-the media, use the @option{--multi-volume} (@option{-M}) option in conjunction with
-the @option{--create} option (@pxref{create}). A @dfn{multi-volume}
-archive can be manipulated like any other archive (provided the
-@option{--multi-volume} option is specified), but is stored on more
-than one tape or disk.
-
-When you specify @option{--multi-volume}, @command{tar} does not report an
-error when it comes to the end of an archive volume (when reading), or
-the end of the media (when writing). Instead, it prompts you to load
-a new storage volume. If the archive is on a magnetic tape, you
-should change tapes when you see the prompt; if the archive is on a
-floppy disk, you should change disks; etc.
+@noindent
+Notice, that the first command had to use @option{-L} option, since
+otherwise @GNUTAR{} will end up writing everything to file
+@file{archive.tar}.
You can read each individual volume of a multi-volume archive as if it
were an archive by itself. For example, to list the contents of one
that volume), use @option{--extract}, again without
@option{--multi-volume}.
-If an archive member is split across volumes (ie. its entry begins on
+If an archive member is split across volumes (i.e. its entry begins on
one volume of the media and ends on another), you need to specify
@option{--multi-volume} to extract it successfully. In this case, you
should load the volume where the archive member starts, and use
volumes as it needs them. @xref{extracting archives}, for more
information about extracting archives.
-@option{--info-script=@var{script-name}}
-(@option{--new-volume-script=@var{script-name}}, @option{-F
-@var{script-name}}) (@pxref{info-script}) is like
-@option{--multi-volume} (@option{-M}), except that @command{tar} does
-not prompt you directly to change media volumes when a volume is
-full---instead, @command{tar} runs commands you have stored in
-@var{script-name}. For example, this option can be used to eject
-cassettes, or to broadcast messages such as @samp{Someone please come
-change my tape} when performing unattended backups. When
-@var{script-name} is done, @command{tar} will assume that the media
-has been changed.
-
Multi-volume archives can be modified like any other archive. To add
files to a multi-volume archive, you need to only mount the last
volume of the archive media (and new volumes, if needed). For all
other operations, you need to use the entire archive.
If a multi-volume archive was labeled using
-@option{--label=@var{archive-label}} (@option{-V @var{archive-label}})
-(@pxref{label}) when it was created, @command{tar} will not
-automatically label volumes which are added later. To label
-subsequent volumes, specify @option{--label=@var{archive-label}} again
-in conjunction with the @option{--append}, @option{--update} or
-@option{--concatenate} operation.
-
-@cindex Labeling multi-volume archives
-@FIXME{example}
-
-@FIXME{There should be a sample program here, including an exit
-before end. Is the exit status even checked in tar? :-(}
-
-@table @option
-@item --multi-volume
-@itemx -M
-Creates a multi-volume archive, when used in conjunction with
-@option{--create} (@option{-c}). To perform any other operation on a multi-volume
-archive, specify @option{--multi-volume} in conjunction with that
-operation.
-
-@item --info-script=@var{program-file}
-@itemx --new-volume-script=@var{program-file}
-@itemx -F @var{program-file}
-Creates a multi-volume archive via a script. Used in conjunction with
-@option{--create} (@option{-c}). @xref{info-script}, dor a detailed discussion.
-@end table
-
+@option{--label=@var{archive-label}} (@pxref{label}) when it was
+created, @command{tar} will not automatically label volumes which are
+added later. To label subsequent volumes, specify
+@option{--label=@var{archive-label}} again in conjunction with the
+@option{--append}, @option{--update} or @option{--concatenate} operation.
+
+@FIXME{This is no longer true: Multivolume archives in @samp{POSIX}
+format can be extracted using any posix-compliant tar
+implementation. The split members can then be recreated from parts
+using a simple shell script. Provide more information about it:}
Beware that there is @emph{no} real standard about the proper way, for
a @command{tar} archive, to span volume boundaries. If you have a
multi-volume created by some vendor's @command{tar}, there is almost
@section Including a Label in the Archive
@cindex Labeling an archive
@cindex Labels on the archive media
+@cindex Labeling multi-volume archives
@UNREVISED
@opindex label
operation, or can compare a previously written archive, to insure that
it is up to date.
-@opindex verify, using with @option{--create}
-@opindex create, using with @option{--verify}
+@xopindex{verify, using with @option{--create}}
+@xopindex{create, using with @option{--verify}}
To check for discrepancies in an archive immediately after it is
written, use the @option{--verify} (@option{-W}) option in conjunction with
the @option{--create} operation. When this option is
distribution tarballs. @xref{Formats,v7}, for the detailed discussion
of this issue and its implications.
-@FIXME{Change the first argument to tar-formats if and when Automake
-people accept my patch to the documentation, and the new Automake is
-out --Sergey 2006-05-25}.
+@FIXME{Change the first argument to tar-formats when the new Automake is
+out. The proposition to add @anchor{} to the appropriate place of its
+docs was accepted by Automake people --Sergey 2006-05-25}.
@xref{Options, tar-v7, Changing Automake's Behavior,
automake, GNU Automake}, for a description on how to use various
archive formats with @command{automake}.
@appendix Genfile
@include genfile.texi
-@node Snapshot Files
-@appendix Format of the Incremental Snapshot Files
-@include snapshot.texi
-
-@node Dumpdir
-@appendix Dumpdir
-@include dumpdir.texi
+@node Tar Internals
+@appendix Tar Internals
+@include intern.texi
@node Free Software Needs Free Documentation
@appendix Free Software Needs Free Documentation
This appendix contains an index of all @GNUTAR{} long command line
options. The options are listed without the preceeding double-dash.
-
-@FIXME{@itemize
-@item Make sure @emph{all} options are indexed.
-@item Provide an index of short options
-@end itemize}
+For a cross-reference of short command line options, @ref{Short Option Summary}.
@printindex op
projects / chaz / tar / blobdiff