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 6.1 Choosing and Naming Archive Files
 =====================================
 
 By default, `tar' uses an archive file name that was compiled when it
 was built on the system; usually this name refers to some physical tape
 drive on the machine.  However, the person who installed `tar' on the
 system may not have set the default to a meaningful value as far as
 most users are concerned.  As a result, you will usually want to tell
 `tar' where to find (or create) the archive.  The `--file=ARCHIVE-NAME'
 (`-f ARCHIVE-NAME') option allows you to either specify or name a file
 to use as the archive instead of the default archive file location.
 
 `--file=ARCHIVE-NAME'
 `-f ARCHIVE-NAME'
      Name the archive to create or operate on.  Use in conjunction with
      any operation.
 
    For example, in this `tar' command,
 
      $ tar -cvf collection.tar blues folk jazz
 
 `collection.tar' is the name of the archive.  It must directly follow
 the `-f' option, since whatever directly follows `-f' _will_ end up
 naming the archive.  If you neglect to specify an archive name, you may
 end up overwriting a file in the working directory with the archive you
 create since `tar' will use this file's name for the archive name.
 
    An archive can be saved as a file in the file system, sent through a
 pipe or over a network, or written to an I/O device such as a tape,
 floppy disk, or CD write drive.
 
    If you do not name the archive, `tar' uses the value of the
 environment variable `TAPE' as the file name for the archive.  If that
 is not available, `tar' uses a default, compiled-in archive name,
 usually that for tape unit zero (i.e., `/dev/tu00').
 
    If you use `-' as an ARCHIVE-NAME, `tar' reads the archive from
 standard input (when listing or extracting files), or writes it to
 standard output (when creating an archive).  If you use `-' as an
 ARCHIVE-NAME when modifying an archive, `tar' reads the original
 archive from its standard input and writes the entire new archive to
 its standard output.
 
    The following example is a convenient way of copying directory
 hierarchy from `sourcedir' to `targetdir'.
 
      $ (cd sourcedir; tar -cf - .) | (cd targetdir; tar -xpf -)
 
    The `-C' option allows to avoid using subshells:
 
      $ tar -C sourcedir -cf - . | tar -C targetdir -xpf -
 
    In both examples above, the leftmost `tar' invocation archives the
 contents of `sourcedir' to the standard output, while the rightmost one
 reads this archive from its standard input and extracts it.  The `-p'
 option tells it to restore permissions of the extracted files.
 
    To specify an archive file on a device attached to a remote machine,
 use the following:
 
      --file=HOSTNAME:/DEV/FILE-NAME
 
 `tar' will set up the remote connection, if possible, and prompt you
 for a username and password.  If you use
 `--file=@HOSTNAME:/DEV/FILE-NAME', `tar' will attempt to set up the
 remote connection using your username as the username on the remote
 machine.
 
    If the archive file name includes a colon (`:'), then it is assumed
 to be a file on another machine.  If the archive file is
 `USER@HOST:FILE', then FILE is used on the host HOST.  The remote host
 is accessed using the `rsh' program, with a username of USER.  If the
 username is omitted (along with the `@' sign), then your user name will
 be used.  (This is the normal `rsh' behavior.)  It is necessary for the
 remote machine, in addition to permitting your `rsh' access, to have
 the `rmt' program installed (this command is included in the GNU `tar'
 distribution and by default is installed under `PREFIX/libexec/rmt',
 where PREFIX means your installation prefix).  If you need to use a
 file whose name includes a colon, then the remote tape drive behavior
 can be inhibited by using the `--force-local' option.
 
    When the archive is being created to `/dev/null', GNU `tar' tries to
 minimize input and output operations.  The Amanda backup system, when
 used with GNU `tar', has an initial sizing pass which uses this feature.
 

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(tar.info.gz) Choosing

(tar.info.gz) Selecting Archive Members