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The `mt' Utility
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   Note: Blocking Factor.

   You can use the `mt' utility to advance or rewind a tape past a
specified number of archive files on the tape.  This will allow you to
move to the beginning of an archive before extracting or reading it, or
to the end of all the archives before writing a new one.

   The syntax of the `mt' command is:

     mt [-f TAPENAME] OPERATION [NUMBER]

   where TAPENAME is the name of the tape device, NUMBER is the number
of times an operation is performed (with a default of one), and
OPERATION is one of the following:

`eof'
`weof'
     Writes NUMBER tape marks at the current position on the tape.

`fsf'
     Moves tape position forward NUMBER files.

`bsf'
     Moves tape position back NUMBER files.

`rewind'
     Rewinds the tape. (Ignores NUMBER).

`offline'
`rewoff1'
     Rewinds the tape and takes the tape device off-line. (Ignores
     NUMBER).

`status'
     Prints status information about the tape unit.

   If you don't specify a TAPENAME, `mt' uses the environment variable
`TAPE'; if `TAPE' is not set, `mt' uses the device `/dev/rmt12'.

   `mt' returns a 0 exit status when the operation(s) were successful,
1 if the command was unrecognized, and 2 if an operation failed.

   If you use `--extract' (`--get', `-x') with the
`--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL') option specified, `tar'
will read an archive label (the tape head has to be positioned on it)
and print an error if the archive label doesn't match the ARCHIVE-NAME
specified.  ARCHIVE-NAME can be any regular expression.  If the labels
match, `tar' extracts the archive.  Note: label.  `tar --list
--label' will cause `tar' to print the label.