This is Info file tar.info, produced by Makeinfo-1.61 from the input
file tar.texinfo.

START-INFO-DIR-ENTRY
* tar: (tar).			Making tape (or disk) archives.
END-INFO-DIR-ENTRY

   This file documents GNU `tar', a utility used to store, backup, and
transport files.

   Copyright (C) 1992, 1994, 1995 Free Software Foundation, Inc.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Foundation.


File: tar.info,  Node: Listing files in an archive bis,  Next: Getting Additional File Information bis,  Prev: How to List Archives,  Up: How to List Archives

Listing the Contents of an Archive
----------------------------------

     *(This message will disappear, once this node revised.)*

   You can list the contents of the archive you just created with
another option of `tar': `--list' (`-t').  To list the contents of an
archive, type:

     % tar --list --file=records

   `tar' will respond:

     blues folk jazz

FIXME: xref Listing Archive Contents
   , for a more detailed tutorial of the `--list' (`-t') operation.
FIXME: xref Listing Contents
   for more information about the `--list' (`-t') operation.
FIXME:

   You can use `--list' (`-t') to output a list of the files in an
archive.  If you use file name arguments with this operation, `tar'
will look in the archive for the files specified and display their
names only if they are, in fact, stored.  You can use `--list' (`-t')
with the `--verbose' (`-v') option to find out the attributes (owner,
size, etc.) of stored files.

   You can list the contents of an archive with another operation of
`tar': `--list' (`-t').  To list the contents of the archive you just
created, type:

     % tar --list --file=records

   `tar' will respond:

     blues folk jazz

FIXME: xref Listing Archive Contents
   , for a more detailed tutorial of the `--list' (`-t') operation.
FIXME: xref Listing Contents
   , for more information about the `--list' (`-t') operation.

   In a previous example, you created the archive `music' in the home
directory.  To list the contents of `music':

   * List the contents of an archive by using `--list' (`-t') with
     `tar'.

   * Specify the name of the archive to be
     listed--`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').

   Thus:

     % tar --list --file=music
     practice/
     practice/blues
     practice/folk
     practice/jazz
     practice/records

   Use `--list' (`-t') to print the names of files stored in an
archive.  If you use file name arguments with this operation, `tar'
prints the names of the specified files if they are stored in the
archive.  If you use a directory name as a file name argument, `tar'
also prints the names of all underlying files, including
sub-directories.  If you use no file name arguments, `tar' prints the
names of all the archive members.

   You can use `--list' (`-t') with the `--verbose' (`-v') option to
print archive members' attributes (owner, size, etc.).

   To list the names of files stored in an archive, use the `--list'
(`-t') operation of `tar'.

   In a previous example, you created the archive `~/music'.  To list
the contents of `music', while in your home directory:

   * List the contents of an archive by using {No Value For "-list"}
     with `tar'.

   * Specify the archive to be listed--`--file=ARCHIVE-NAME' (`-f
     ARCHIVE-NAME').

   Thus:

     % tar --list --file=music
     practice/
     practice/blues
     practice/folk
     practice/jazz
     practice/records


File: tar.info,  Node: Getting Additional File Information bis,  Next: List A Specific File in an Archive bis,  Prev: Listing files in an archive bis,  Up: How to List Archives

Getting Additional File Information
-----------------------------------

     *(This message will disappear, once this node revised.)*

   When you specify the `--verbose' (`-v') option in conjunction with
`--list' (`-t'), `tar' will print additional information about the
files being listed (file protection, owner and group ID, size, and date
and time of creation).  The example above, in verbose mode, would be:

     % tar --list --verbose --file=music
     drwxrwxrwx myself/user 0 May 31 21:49 1990 practice/
     -rw-rw-rw- myself/user 42 May 21 13:29 1990 practice/blues
     -rw-rw-rw- myself/user 62 May 23 10:55 1990 practice/folk
     -rw-rw-rw- myself/user 40 May 21 13:30 1990 practice/jazz
     -rw-rw-rw- myself/user 10240 May 31 21:49 1990 practice/records
     %

   Note that using `--verbose' (`-v') with `--list' (`-t') does not
cause `tar' to print the names of files as they are being acted on,
though the `--verbose' (`-v') option will have this effect with all
other operations.

   To get more information when you list the names of files stored in an
archive, specify the `--verbose' (`-v') option in conjunction with
`--list' (`-t').

   `tar' will print archive member's file protection, owner and group
ID, size, and date and time of creation.

   For example:

     % tar --list --verbose --file=music
     drwxrwxrwx myself/user 0 May 31 21:49 1990 practice/
     -rw-rw-rw- myself/user 42 May 21 13:29 1990 practice/blues
     -rw-rw-rw- myself/user 62 May 23 10:55 1990 practice/folk
     -rw-rw-rw- myself/user 40 May 21 13:30 1990 practice/jazz
     -rw-rw-rw- myself/user 10240 May 31 21:49 1990 practice/records
     %

   Note that when you use `--verbose' (`-v') with `--list' (`-t'),
`tar' doesn't print the names of files as they are being acted on,
though the `--verbose' (`-v') option will have this effect when used
with all other operations.


File: tar.info,  Node: List A Specific File in an Archive bis,  Next: Listing the Contents of a Stored Directory ter,  Prev: Getting Additional File Information bis,  Up: How to List Archives

List A Specific File in an Archive
----------------------------------

     *(This message will disappear, once this node revised.)*

FIXME:
   To to see if a particular file is in an archive, specify the name of
the file in question as a file name argument while specifying the
`--list' (`-t') operation.  For example, if you wanted to see if the
file `folk' were in the archive file `music', you would:

   * Invoke `tar', and specify the operation to list the contents of an
     archive--`--list' (`-t').

   * Specify the name of the archive file to be acted
     on--`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').

   * Specify the name of the file `tar' is to look for, as a file name
     argument.  Because `tar' preserves paths, file names must be
     specified as they appear in the archive (ie.. as they are relative
     to the directory from which the archive was created).
     FIXME: xref -P

   Type:

     % tar --list --file=music practice/folk

`tar' responds:

     practice/folk

If the file were not in the archive (for example, the file
`practice/rock'), the example above would look like:

     % tar --list --file=music practice/rock
     tar: practice/rock not found in archive

   The `--verbose' (`-v') option does not have any effect on execution
of the `--list' (`-t') operation when you have specified file name
arguments.
FIXME: this is a bug (?)

   To to see if a particular file is in an archive, use the name of the
file in question as a file name argument while specifying the `--list'
(`-t') operation.  For example, to see whether the file `folk' is in the
archive file `music', do the following:

   * Invoke `tar', and specify the `--list' (`-t') operation.

   * Specify the archive file to be acted on--`--file=ARCHIVE-NAME'
     (`-f ARCHIVE-NAME').

   * Specify the files to look for, by typing their names as file name
     arguments.  You have to type the file name as it appears in the
     archive (normally, as it is relative to the relative to the
     directory from which the archive was created).
     FIXME: xref absolute-names

   Type:

     % tar --list --file=music practice/folk

   `tar' responds:

     practice/folk

   If the file were not stored in the archive (for example, the file
`practice/rock'), the example above would look like:

     % tar --list --file=music practice/rock
     tar: practice/rock not found in archive

   If you had used `--verbose' (`-v') mode, the example above would
look like:

     % tar --list --file=music practice/folk
     -rw-rw-rw- myself/user 62 May 23 10:55 1990 practice/folk


File: tar.info,  Node: Listing the Contents of a Stored Directory ter,  Prev: List A Specific File in an Archive bis,  Up: How to List Archives

Listing the Contents of a Stored Directory
------------------------------------------

     *(This message will disappear, once this node revised.)*

   To get information about the contents of an archived directory, use
the directory name as a file name argument in conjunction with `--list'
(`-t').  To find out file attributes, include the `--verbose' (`-v')
option.

   For example, to find out about files in the directory `practice', in
the archive file `music', type:

     % tar --list --file=music practice

   `tar' responds:

     drwxrwxrwx myself/user 0 May 31 21:49 1990 practice/
     -rw-rw-rw- myself/user 42 May 21 13:29 1990 practice/blues
     -rw-rw-rw- myself/user 62 May 23 10:55 1990 practice/folk
     -rw-rw-rw- myself/user 40 May 21 13:30 1990 practice/jazz
     -rw-rw-rw- myself/user 10240 May 31 21:49 1990 practice/records

   When you use a directory name as a file name argument, `tar' acts on
all the files (including sub-directories) in that directory.


File: tar.info,  Node: How to Extract Members from an Archive,  Next: How to Add Files to Existing Archives,  Prev: How to List Archives,  Up: Tutorial

How to Extract Members from an Archive
======================================

     *(This message will disappear, once this node revised.)*

   In order to extract members from an archive, use the `--extract'
(`-x') option.  Specify the name of the archive with
`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').  To extract specific archive
members, give their member names as arguments.  It essential to give
their exact member name, as printed by `--list' (`-t').  This will
create a copy of the archive member, with a file name the same as its
name in the archive.

   Keeping the example of the two archives created at the beginning of
this tutorial, `tar --extract --file=afiles.tar apple' would create a
file `apple' in the current directory with the contents of the archive
member `apple'.  It would remove any file named `apple' already present
in the directory, but it would not change the archive in any way.

   Remember that specifying the exact member name is important.  `tar
--extract --file=bfiles.tar baloons' will fail, because there is no
member named `baloons'.  To extract the member named `./baloons' you
would need to specify `tar --extract --file=bfiles.tar ./baloons'.  To
find the exact member names of the members of an archive, use `--list'
(`-t').
FIXME: xref Listing Archives.

   If you do not list any archive member names, then `--extract' (`-x')
will extract all the members of the archive.

   If you give the `--verbose' (`-v') option, then `--extract' (`-x')
will print the names of the archive members as it extracts them.

* Menu:

* Extracting Files bis::
* Extracting Files from an Archive ter::
* Extracting Specific Files ter::
* Extracting Directories ter::


File: tar.info,  Node: Extracting Files bis,  Next: Extracting Files from an Archive ter,  Prev: How to Extract Members from an Archive,  Up: How to Extract Members from an Archive

Extract Files from an Archive into Your Current Directory
---------------------------------------------------------

     *(This message will disappear, once this node revised.)*

   Obviously, the ultimate goal of `tar' users is to eventually get
their files back.  To do this, use the `--extract' (`-x') or `--get'
operation.  `--extract' (`-x') can be used to retrieve individual files
from an archive, or can be used to write all the files in the archive
back into the file system.

   In the previous example you concatenated two archives, `music', and
`practice/records'.  To now retrieve the complete contents of `music'
(the target file in the concatenation process), you would, from the
home directory:

   * Invoke `tar' and specify the operation to extract files from an
     archive (`--extract' (`-x') or `--get'.

   * Specify the name of the archive the files will be extracted
     from--`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').

   * Specify the names of the files you wish to extract, as file name
     arguments (in this case you want to extract the entire archive, so
     you don't need to specify anything).

     % tar --extract --file=music
     tar: Could not make directory practice : File exists

Because the files stored originally in `music' were stored as files in
a subdirectory (not as files in the working directory), they are stored
in the archive with a leading directory name--`tar', in restoring them,
has tried to recreate that directory and failed: the directory already
exists.  The extraction has not been aborted, however.  If you now
change into the `practice' directory and generate a directory listing,
you will find that `jazz', which we removed in an earlier example, has
been resurrected.

     % cd practice
     % ls
     blues	   classical  folk	 jazz	    records    rock

   If you look more closely at the files in the directory, however, you
will find that `blues' and `folk' are, in fact, the original versions
of the file, which were stored in `music' at the beginning of the
tutorial.  `tar', in extracting the original files from `music', has
overwritten the existing files in the file system.

   While the newer versions of the files were stored in `records'
above, they can no longer be extracted from it.  `records' too was
archived by `tar' when the `practice' directory was stored in the
archive file `music', and was restored to its older incarnation when
the files in `practice' were overwritten.  However, the newer version
of `records' was concatenated with `music'.  The contents of the newer
version of `records', therefore, should have been extracted when all
the contents of `music' were extracted.  They were.  `tar' has restored
them into the working directory using the names with which they were
originally stored.  Because they were originally stored as part of
`records', in the `practice' directory, they had no preceeding
directory stored as part of their file names.  To find the latest
versions of `blues', `folk', `jazz', `rock' and `classical', look in
your home directory.

   You may wish to restore the files in your `practice' directory to
their last state before we extracted the files from `music'.  Rather
than moving the files from your home directory to the `practice'
subdirectory, you can run the same extraction procedure as above using
the `practice' subdirectory as your working directory:

     % cd practice
     % tar --extract --verbose --file=~/music
     practice/
     practice/blues
     practice/folk
     practice/jazz
     practice/records
     blues
     folk
     jazz
     blues
     rock
     blues
     classical
     %

If you now examine the files in the practice directory, you will find
that the files have been restored to their previous, newer, states.
The old versions of the files, which were stored in `music' with a
preceeding directory name, have been written into a newly created
subdirectory under the working directory (which is your `practice'
subdirectory).  The new subdirectory is also called `practice'.


File: tar.info,  Node: Extracting Files from an Archive ter,  Next: Extracting Specific Files ter,  Prev: Extracting Files bis,  Up: How to Extract Members from an Archive

Extracting Files from an Archive
--------------------------------

     *(This message will disappear, once this node revised.)*

   Creating an archive is only half the job--there would be no point in
storing files in an archive if you couldn't retrieve them.  To extract
files from an archive, use the `--extract' (`-x') operation.

   To extract specific files, use their names as file name arguments.
If you use a directory name as a file name argument, `tar' extracts all
the files (including subdirectories) in that directory.  If you don't
use any file name arguments, `tar' extracts all the files in the
archive.

   Note: `tar' will extract an archive member into the file system
without checking to see if there is already a file with the archive
member's file name.  If there is a file with that name, `tar' will
*overwrite* that file and its contents will be lost.
FIXME: xref keep-old


File: tar.info,  Node: Extracting Specific Files ter,  Next: Extracting Directories ter,  Prev: Extracting Files from an Archive ter,  Up: How to Extract Members from an Archive

Extracting Specific Files
-------------------------

     *(This message will disappear, once this node revised.)*

   To extract specific files, specify them using file name arguments.

   In an example above, you created the archive file
`~/practice/records', which contained the files `blues', `folk' and
`jazz' in the `practice' directory.  If, for some reason, you were to
lose one of those text files (`rm ~/practice/blues'), you could extract
it from the archive file.

   First, change into the `practice' directory.  Then,

   * Invoke `tar' and specify the `--extract' (`-x') or `--get'
     operation.

   * Specify the archive that the files will be extracted
     from--`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').

   * Specify the files to extract, using file name arguments (if you
     don't specify any files, `tar' extracts all the archive members)

     % tar --extract --file=records blues

   If you list the contents of the directory, you will see that `blues'
is back:

     % ls
     folk
     jazz
     records
     blues


File: tar.info,  Node: Extracting Directories ter,  Prev: Extracting Specific Files ter,  Up: How to Extract Members from an Archive

Extracting Directories
----------------------

     *(This message will disappear, once this node revised.)*

   To extract a directory and all the files it contains, use the
directory's name as a file name argument in conjunction with `tar
+extract'.  Remember-`tar' stores and extracts file names relative to
the working directory.

   In a previous example you stored the directory `~/practice' in the
archive file `~/music'.  If you delete the contents of `practice', you
can restore them using `tar'.

   First, change into the `practice' subdirectory (`cd ~/practice').
Then, remove all the files in `~/practice' (`rm *').  If you list the
contents of the directory, you should now see that it is empty:

     %ls
     %

   Let's try to restore the contents of `practice' by extracting them
from the archive file `~/music':

     tar --extract --file=~/music practice

   Now, list the contents of `practice' again:

     %ls
     practice

   What happened to the files?  When you created `~/music', your
working directory was your home directory.  When you extracted
`~/music', your working directory was `~/practice'. `tar' stored the
files in `practice' relative to your home directory, and then extracted
them relative to `~/practice'.  The files are now in a new
subdirectory, called `~/practice/practice'.

   To restore your files to their old positions, delete the new
directory and its contents, and then redo the example above with your
home directory as the working directory:

     % rm ~/practice/practice/*
     % rmdir practice
     % cd ..
     % tar --extract --file=music practice

   (`tar' will report that it is unable to create the directory
`~/practice' because it already exists.  This will not effect the
extraction of the other archive members.)


File: tar.info,  Node: How to Add Files to Existing Archives,  Next: How to Delete Members from Archives,  Prev: How to Extract Members from an Archive,  Up: Tutorial

How to Add Files to Existing Archives
=====================================

     *(This message will disappear, once this node revised.)*

   If you want to add files to an existing archive, then don't use
`--create' (`-c').  That will erase the archive and create a new one in
its place.  Instead, use `--append' (`-r').  The command `tar --append
--file=afiles.tar arbalest' would add the file `arbalest' to the
existing archive `afiles.tar'.  The archive must already exist in order
to use `--append' (`-r').

   As with `--create' (`-c'), the member names of the newly added files
will be the exact same as their names given on the command line.  The
`--verbose' (`-v') option will print out the names of the files as they
are written into the archive.

   If you add a file to an archive using `--append' (`-r') with the
same name as an archive member already present in the archive, then the
old member is not deleted.  What does happen, however, is somewhat
complex.
FIXME: xref Multiple Members with the Same Name.
   If you want to replace an archive member, use `--delete' first, and
then use `--append' (`-r').

FIXME: we want people to use the script for backups, so I an not going
FIXME: to use backups as an explanation in the tutorial.  (people can still
FIXME: do it if they really want to)

   While you can use `tar' to create a new archive every time you want
to store a file, it is more sometimes efficient to add files to an
existing archive.

   To add new files to an existing archive, use the `--append' (`-r')
operation.  To add newer versions of archive members to an archive, use
the `--update' (`-u') operation.

   While you can use `tar' to create an archive of an entire directory
or directory tree, it is more efficient when performing backups to only
archive those files which have been newly created or changed since the
last backup.

   To add new files to an existing archive, or to add newer versions of
old files, you can use the `--append' (`-r') operation, or the
`--update' (`-u') operation.

* Menu:

* Append bis::
* Update bis::
* Concatenate bis::


File: tar.info,  Node: Append bis,  Next: Update bis,  Prev: How to Add Files to Existing Archives,  Up: How to Add Files to Existing Archives

Appending Files to an Archive
-----------------------------

     *(This message will disappear, once this node revised.)*

   The simplest method of adding a file to an already existing archive
is the `--append' (`-r') operation, which writes the files specified
into the archive without regard to whether or not they are already
among the archived files.  When you use `--append' (`-r') you must
specify file name arguments, there is no default.  If you specify a
file that already exists in the archive another copy of the file will
be added to the end of the archive anyway.

   In the previous examples you created a file called `rock' in the
practice directory which did not exist in either the archive file
`records', in the practice directory, or the archive file `music', in
the home directory.  To add `rock' to `records', you would, while in
the practice directory:

   * Invoke `tar' and specify the operation to add a file--`--append'
     (`-r').

   * Specify the name of the archive to which the file will be
     added--`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').

   * Specify the name(s) of the file(s) to be added to the archive as
     the file name argument(s)

     % tar --append --file=records rock

If you now use the `--list' (`-t') operation, you will see that `rock'
has been added to the archive:

     % tar --list --file=records
     blues
     folk
     jazz
     rock

   While all newly created files have now been added to `records', it
is still not current with respect to the contents of the practice
directory.  If you recall from the examples using `--compare' (`-d')
above, `blues' was changed after the archive `records' was created.  It
is simple, however, to use `--append' (`-r') to correct the problem:

     % tar --append --verbose --file=records blues
     blues

Because you specified the `--verbose' (`-v') option, `tar' has printed
the name of the file being appended as it was acted on.  If you now use
`tar' with the `--list' (`-t') option specified to get the contents of
the archive, you will optain the following:

     % tar --list -f records
     blues
     folk
     jazz
     rock
     blues

The newest version of `blues' is now at the end of the archive.
Because files are extracted from archives in the order in which they
appear in the archive, and because extracted files are given the same
names in the file system as they are stored under in the archive, when
the files in `records' are extracted the newer version of `blues'
(which has the same name as the older) will overwrite the version
stored first.
FIXME: xref Keep Old Files

FIXME: --update wont take a directory argument if files that have been
FIXME: archived from that directory are now no longer in it.  (I assume
FIXME: because it looks in the archive first for the directory listing.)
FIXME: this is a bug

   The simplest method of adding a file to an existing archive is the
`--append' (`-r') operation, which writes files into the archive
without regard to whether or not they are already archive members.
When you use `--append' (`-r') you must use file name arguments; there
is no default.  If you specify a file that is already stored in the
archive, `tar' adds another copy of the file to the archive.

   If you have been following the previous examples, you should have a
text file called `~/practice/rock' which has not been stored in either
the archive file `~/practice/records', or the archive file `~/music'.
To add `rock' to `records', first make `practice' the working directory
(`cd practice').  Then:

   * Invoke `tar' and specify the `--append' (`-r') operation.

   * Specify the archive to which the file will be
     added--`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').

   * Specify the files to be added to the archive, using file name
     arguments

   For example:

     % tar --append --file=records rock

   If you list the archive members in `records', you will see that
`rock' has been added to the archive:

     % tar --list --file=records
     blues
     folk
     jazz
     rock

FIXME: this should be some kind of node.

   You can use `--append' (`-r') to keep archive members current with
active files.  Because `--append' (`-r') stores a file whether or not
there is already an archive member with the same file name, you can use
`--append' (`-r') to add newer versions of archive members to an
archive.  When you extract the file, only the version stored last will
wind up in the file system.  Because `--extract' (`-x') extracts files
from an archive in sequence, and overwrites files with the same name in
the file system, if a file name appears more than once in an archive
the last version of the file will overwrite the previous versions which
have just been extracted.

   If you recall from the examples using `--compare' (`-d') above,
`blues' was changed after the archive `records' was created. It is
simple, however, to use `--append' (`-r') to add the new version of
`blues' to `records':

     % tar --append --verbose --file=records blues
     blues

   If you now list the contents of the archive, you will obtain the
following:

     % tar --list -f records
     blues
     folk
     jazz
     rock
     blues

   The newest version of `blues' is at the end of the archive.  When the
files in `records' are extracted, the newer version of `blues' (which
has the same name as the older) will overwrite the version stored
first.  When `--extract' (`-x') is finished, only the newer version of
`blues' is in the file system.
FIXME: xref keep-old-files


File: tar.info,  Node: Update bis,  Next: Concatenate bis,  Prev: Append bis,  Up: How to Add Files to Existing Archives

Updating Files in an Archive
----------------------------

     *(This message will disappear, once this node revised.)*

   While the `--append' (`-r') option is useful for updating files in an
archive, to keep an archive current with `--append' (`-r') you must
first use the `--compare' (`-d') or `--list' (`-t') options to determine
what files have been changed (or be willing to waste space by adding
identical copies of archived files to the ends of archives).  It is
simpler to use the `--update' (`-u') operation, and let `tar' do the
work for you.

   The `--update' (`-u') option causes `tar' to add files to the end of
an archive, just like the `--append' (`-r') option.  When you invoke
`tar' with the `--update' (`-u') option specified you must specify file
name arguments.  Unlike `--append' (`-r'), the `--update' (`-u') option
causes `tar' to check the archive to be updated to see if the specified
file is already stored.  If the file (or one with the same name) is
already in the archive, `tar' checks the modification date of the file
in the archive and compares it to the file of the same name in the file
system.  The file is only appended to the archive if it is new or if
its modification date has changed to a later one.
FIXME: xref After-Date

   To see the `--update' (`-u') option at work, create a new file,
`classical', in your practice directory, and add a line to the file
`blues', using any text editor.  Then invoke `tar' with the `--update'
(`-u') operation and the `--verbose' (`-v') option specified, using the
names of all the files in the practice directory as file name arguments:

     % tar --update --verbose --file=records blues folk rock classical
     blues
     classical
     %

Because we have specified verbose mode, `tar' prints out the names of
the files it is working on, which in this case are the names of the
files that needed to be updated.  If you now invoke `tar' with the
`--list' (`-t') operation specified, to generate a listing of the files
in the archive, you will see that `blues' and `classical' have been
added to its end.

   [The reason `tar' does not overwrite the older file when updating it
is because writing to the middle of a section of tape is a difficult
process.  Tapes are not designed to go backward.  Even if they were,
imagine what would happen if the newer version were longer than the
older one.]

   To keep archive members up to date with their counterparts of the
same name in the file system, use the `--update' (`-u') option.  This
adds a specified file to an archive if no file of that name is already
stored in the archive.  If there is already an archive member with the
same name, `tar' checks the modification date of the archive member,
and adds the file only if its modification date is later.  If a file is
stored in the archive but no longer exists under the same name in the
active file system, `tar' reports an error.

   You could use the `--append' (`-r') option to keep an archive
current, but do so you would either have to use the `--compare' (`-d')
and `--list' (`-t') options to determine what files needed to be
re-archived (which could waste a lot of time), or you would have to be
willing to add identical copies of already archived files to the
archive (which could waste a lot of space).

   You must use file name arguments with the `--update' (`-u')
operation-if you don't specify any files, `tar' won't act on any files.

   To see the `--update' (`-u') option at work, create a new file,
`~/practice/classical', and modify the file `~/practice/blues' (you can
use a text editor, such as Emacs, to do both these things).  Then, with
`practice' as your working directory, invoke `tar' with the `--update'
(`-u') option, using the names of all the files in the practice
directory as file name arguments, and specifying the `--verbose' (`-v')
option:

     % tar --update --verbose --file=records blues folk rock classical
     blues
     classical
     %

   Because you specified verbose mode, `tar' printed out the names of
the files it acted on.  If you now list the archive members of the
archive, (`tar --list --file=records'), you will see that the file
`classical' and another version of the file `blues' have been added to
`records'.

   Note: When you update an archive, `tar' does not overwrite old
archive members when it stores newer versions of a file.  This is
because archive members appear in an archive in the order in which they
are stored, and some archive devices do not allow writing in the middle
of an archive.


File: tar.info,  Node: Concatenate bis,  Prev: Update bis,  Up: How to Add Files to Existing Archives

Concatenating Archives
----------------------

     *(This message will disappear, once this node revised.)*

   Rather than adding individual files onto the end of an archive, it
may be more convenient to add archives themselves onto the end of an
archive.  While it may seem intuitive to use `cat', the utility for
adding files together, for this purpose, archives created by `tar'
incorporate an end of file marker which must be removed if the
concatenated archives are to be read properly as one archive
FIXME: xref Ignore zeros.
   To add archives to the end of another archive, therefore, you should
use the `--concatenate' (`-A') operation.

   In earlier examples you created an archive file, `music', in your
home directory.  You have, however, since changed the contents of the
`practice' directory which was stored in that archive.  `records', the
archive file in the `practice' directory, has recently been updated,
and contains a current version of the files in `practice'.  Rather than
update the contents of `music', let's add `records' to it.

   * Change into the home directory (`cd ..')

   * Invoke `tar', and specify the operation to add archives to the end
     of another archive--`--concatenate' (`-A').

   * Specify the name of the archive file to be added
     to--`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').

   * Specify the file name arguments, which are, unusually, the names of
     archive files.  Remember to include the directory name in the file
     name, if the archive file is not in your working directory.

     % cd ..
     % tar --concatenate --file=music practice/records

   Rather than list the new contents of `music', let's extract all the
files and see what happens.

   To concatenate archive files, use the `--concatenate' (`-A') option.
This operation adds other archives to the end of an archive. While it
may seem intuitive to concatenate archives using `cat', the utility for
adding files together, archive files which have been "catted" together
cannot be read properly by `tar'.  Archive files incorporate an end of
file marker-if archives are concatenated using `cat', this marker will
appear before the end of the new archive.  This will interfere with
operations on that archive.
FIXME: xref ignore-zeros

   In earlier examples, you stored the `~/practice' directory in an
archive file, `~/music'.  If you have been following the examples, you
have since changed the contents of the `~/practice' directory.  There
is a current version of the files in the `practice' directory, however,
stored in the archive file `~/practice/records'.

   To store current versions of the files in `practice' in the archive
file `music', you can use `--concatenate' (`-A') to add the archive file
`~/practice/records' to `music'.  First, make sure you are in your home
directory (`cd ~').  Then:

   * Invoke `tar', and specify the `--concatenate' (`-A') operation.

   * Specify the archive file to be added to--`--file=ARCHIVE-NAME'
     (`-f ARCHIVE-NAME').

   * Specify the archives to be added, using file name arguments.  In
     this case, the file name arguments are, unusually, the names of
     archive files.  (Remember to include the path in the archive name,
     if the archive file is not in your working directory.)

     % cd ~
     % tar --concatenate --file=music practice/records

   If you now list the contents of the `music', you see it now contains
the archive members of `practice/records':

     %tar --list --file=music
     blues
     folk
     jazz
     rock
     blues
     practice/blues
     practice/folk
     practice/jazz
     practice/rock
     practice/blues
     practice/classical


File: tar.info,  Node: How to Delete Members from Archives,  Prev: How to Add Files to Existing Archives,  Up: Tutorial

How to Delete Members from Archives
===================================

     *(This message will disappear, once this node revised.)*

   You can delete members from an archive using `--delete'.  Specify
the name of the archive with `--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').
List the member names of the members to be deleted.  (If you list no
member names, then nothing will be deleted.)  The `--verbose' (`-v')
option will cause `tar' to print the names of the members as they are
deleted.  As with `--extract' (`-x'), it is important that you give the
exact member names when using `tar --delete'.  Use `--list' (`-t') to
find out the exact member names in an archive.
FIXME: xref Listing Archives.

   The `--delete' option only works with archives stored on disk.  You
cannot delete members from an archive stored on a tape.

   In some instances, it may be advantageous to remove some files from
an archive stored on disk (it is never advantageous to delete files from
an archive stored on tape--the linear nature of tape storage makes this
action likely to scramble the archive).  You can use the `--delete'
operation to remove files from an archive.  The names of files to be
removed must be specified to `tar' as file name arguments.  All
versions of the named file are removed from the archive.  Execution of
the `--delete' operation can be very slow.

   To delete all versions of the file `blues' from the archive
`records' in the `practice' directory, make sure you are in that
directory, and then,

   * List the contents of the archive file `records' (see above for the
     steps involved) to insure that the file(s) you wish to delete are
     stored in the archive.  (This step is optional)

   * Invoke `tar' and specify the operation to delete files from an
     archive (`--delete')

   * Specify the name of the archive file that the file(s) will be
     deleted--`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').

   * Specify the name(s) of the file(s) to be deleted, as file name
     arguments

   * List the contents of the archive file again--note that the files
     have been removed.  (this step is also optional)

     % tar --list --file=records
     blues
     folk
     jazz
     % tar --delete --file=records blues
     % tar --list --file=records
     folk
     jazz
     %

   In some instances, you may want to remove some files from an archive
stored on disk

     *Caution:* you should never delete files from an archive stored on
     tape-because of the linear nature of tape storage, doing this is
     likely to scramble the archive.

   To remove archive members from an archive, use the `--delete'
operation.  You must specify the names of files to be removed as file
name arguments.  All versions of the named file are removed from the
archive.

   Execution of the `--delete' operation can be very slow.

   To delete all versions of the file `blues' from the archive
`records' in the `practice' directory, make sure you are in that
directory, and then:

   * List the contents of the archive file `records' (see above for the
     steps involved) to insure that the file(s) you wish to delete are
     stored in the archive.  (This step is optional)

   * Invoke `tar' and specify the `--delete' operation (`--delete').

   * Specify the name of the archive file that the file(s) will be
     deleted from--`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME').

   * Specify the files to be deleted, using file name arguments.

   * List the contents of the archive file again--note that the files
     have been removed.  (this step is also optional)

     % tar --list --file=records
     blues
     folk
     jazz
     % tar --delete --file=records blues
     % tar --list --file=records
     folk
     jazz
     %


File: tar.info,  Node: Invoking tar,  Next: Basic tar Operations,  Prev: Tutorial,  Up: Top

Invoking GNU `tar'
******************

     *(This message will disappear, once this node revised.)*

* Menu:

* Synopsis::
* Option Styles::
* Options::


File: tar.info,  Node: Synopsis,  Next: Option Styles,  Prev: Invoking tar,  Up: Invoking tar

General Synopsis of `tar'
=========================

   The usual way to invoke `tar' is:

     tar OPTION... [NAME]...

   You can actually type in arguments in any order, but in this manual
the options always precede the other arguments, to make examples easier
to understand.  Further, the option stating the main operation mode
(the `tar' "main command") is usually given first.

   There are surely many options to `tar', and three different style
for writing them: mnemonic options, short options, and old options.
These styles are discussed below.  Some options make sense with any
main command, while others are meaningful only with particular main
commands.  One option should state the main command, all others are
truly optional.

   Beware that `tar' options are case sensitive.  For example, {No
Value For "List"} or {No Value For "List"} options are not equivalent to
`--list' (`-t'), in fact, they do not even exist.  Options `-T' and
`-t' are different options, the first requires an argument for stating
the name of a file providing a list of NAMEs, the second does not
require an argument and is another way to write `--list' (`-t').

   Each NAME in the synopsis above is interpreted as an archive member
name when the main command is one of `--compare' (`-d'), `--delete',
`--extract' (`-x'), `--list' (`-t') or `--update' (`-u').  For all
other main commands, NAMEs are interpreted as the names of files
(including directories) in the file system.  `tar' interprets relative
file names as being relative to the working directory.

   `tar' will make all file names relative (by removing leading `/'s
when archiving or restoring files), unless you specify otherwise (using
the `--absolute-names' (`-P') option).
FIXME: xref File Name
Interpretation
   , for more information about `--absolute-names' (`-P').
FIXME: yet another node name that is probably wrong.

   The distinction between file names and archive member names is
especially important when shell globbing is used, and sometimes a
source of confusion for newcomers.  "Globbing" is the operation by
which "wildcard" characters, `*' or `?' for example, are replaced and
expanded into all existing files matching the given pattern.  The
problem is that shells may only glob using existing files in the file
system.  Only `tar' may glob on archive members, so when needed, you
must ensure that wildcard characters reach `tar' without being
interpreted by the shell first.  Using a backslash before `*' or `?',
or putting the whole argument between quotes, is usually sufficient for
this.

   Even if NAMEs are often specified on the command line, they can also
be read from a text file in the file system, using the
`--files-from=FILE-OF-NAMES' (`-T FILE-OF-NAMES') option.

   Each of the following subsection groups some options under a common
functionality.

   You can use `tar' to store files in an archive, to extract them from
an archive, and to do other types of archive manipulation.  The primary
argument to `tar', which is called the "operation", specifies which
action to take.  The other arguments to `tar' are either "options",
which change the way `tar' performs an operation, or "file names",
which specify the files `tar' is to act on.  The typical `tar' command
line syntax is:

   GNU `tar' returns only a few exit statuses.  I'm really aiming
simplicity in that area, for now.  If you are not using the `--compare'
(`-d') option, zero means that everything went well, besides maybe
innocuous warnings.  Nonzero means that something went wrong.  Right
now, as of today, "nonzero" is almost always 2, except for remote
operations, where it may be 128.


File: tar.info,  Node: Option Styles,  Next: Options,  Prev: Synopsis,  Up: Invoking tar

Many Styles for Options
=======================

* Menu:

* Mnemonic Options::
* Short Options::
* Old Options::
* Mixing Styles::


File: tar.info,  Node: Mnemonic Options,  Next: Short Options,  Prev: Option Styles,  Up: Option Styles

Mnemonic Option Style
---------------------

   Each OPTION has at least one mnemonic option name starting with two
dashes in a row, v.g. `--list' (`-t').  The mnemonic option names are
more legible than the corresponding short or old option names, you may
prefer them if you highly praise clarity.  It sometimes happens that a
single mnemonic option has many different different names, which are
then synonymous.  In addition, mnemonic option names can be given unique
abbreviations.  For example, `--cre' can be used in place of `--create'
because there is no other mnemonic option which begins with `cre'.

   Some options require an argument.  This is the case of the
`--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME') option, which tells the name
of the `tar' archive.  The argument of a mnemonic option is usually
given right after the option itself, and introduced by an equal sign.
For example, the `--file=ARCHIVE-NAME' (`-f ARCHIVE-NAME') option is
given the `archive.tar' file as argument by using the notation
`--file=archive.tar' for the mnemonic option.

   Mnemonic options are meant to be obvious and easy to remember,
possibly more so than their corresponding short options, below.  For
example:

     tar --create --verbose --block-size=20 --file=/dev/rmt0

gives a fairly good set of hints about what the command does, even for
those not fully acquainted with `tar'.


File: tar.info,  Node: Short Options,  Next: Old Options,  Prev: Mnemonic Options,  Up: Option Styles

Short Option Style
------------------

   Most options, but not all of them, also have a short option name
starting with a single dash, and followed by a single character, v.g.
`-t'.  In fact, `-t' is exactly the short option name for the mnemonic
option `--list' (`-t'), both having exactly the same meaning.  The
forms are absolutely identical in function.

   The short option names are faster to type than mnemonic option names.
All along this manual, whenever a mnemonic option name is given, its
equivalent short option name follows between parentheses, if such a
short option name exists.

   Short options which require arguments use the immediately following
argument, so it may be thought as being merely introduced right after
it, usually separate by white space.  It is also possible to stick the
argument right after the short option name, using no intervening space.
So one might write `-f archive.tar' or `-farchive.tar' instead of
using `--file=archive.tar'.  Both `--file=ARCHIVE-NAME' and
`-f ARCHIVE-NAME' denote the option to give the archive a non-default
name, which in the example is `archive.tar'.  When the option is given
separately, its argument follows it, as is usual for Unix programs.
For example:

     tar -c -v -b 20 -f /dev/rmt0

   Short options letters may be lumped together, but contrary to old
options, they do not necessarily have to.  When short options are
nevertheless coalesced, use a single dash for them all.  Only the last
one in such a set is allowed to have an argument.  (Clustering many
options, the last of which taking an argument, seems to be fairly
opaque writing to me.  I would even like that GNU `getopt' be helpful
enough to make this illegal.)

   If you move short options in the command, be sure to move their
arguments along with them, if any.

