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MT(1)                       NetBSD Reference Manual                      MT(1)


NAME

     mt - magnetic tape manipulation


SYNOPSIS

     mt [-f tapename] command [count]


DESCRIPTION

     The mt program is used to give commands to a magnetic tape drive.  By de-
     fault mt performs the requested operation once.  Operations may be per-
     formed multiple times by specifying count.

     Note that tapename must reference a raw (not block) tape device.  If
     tapename is of the form "host:tapename", or "user@host:tapename", mt
     writes to the named tape device on the remote host using rmt(8).

     The rmt(8) process on the remote host is typically initiated via rsh(1),
     although an alternate method such as ssh(1) can be specified via the
     RCMD_CMD environment variable.

     The available commands are listed below.  Only as many characters as are
     required to uniquely identify a command need be specified.

     asf        Absolute space to file count.

     eof, weof  Write count end-of-file marks at the current position on the
                tape.

     fsf        Forward space count files.

     fsr        Forward space count records.

     bsf        Back space count files.

     bsr        Back space count records.

     rewind     Rewind the tape (Count is ignored).

     offline, rewoffl
                Rewind the tape and place the tape unit off-line (Count is ig-
                nored).

     status     Print status information about the tape unit (Count is ig-
                nored).

     retension  Retensions the tape (if this operation is supported by the
                tape unit, count is ignored).

     erase      Erases the tape (if this operation is supported by the tape
                unit, count is ignored).

     eew        Enable or disabled early warning EOM behaviour.  Count is set
                to nonzero to enable, zero to disable.

     eom        Forward space to the end of the media (Count is ignored).

     blocksize  Set the tape blocksize to count bytes.  A count of zero sets
                variable blocksize.

     density    Set the tape density code to count as specified in the SCSI-2
                specification.

     rdspos     Read the logical block position of the tape (not all tape
                drives support this feature, count is ignored).

     rdhpos     Read the hardware block position of the tape (not all tape
                drives support this feature, count is ignored).

     setspos    Set the logical block position of the tape to count (not all
                tape drives support this feature).

     sethpos    Set the hardware block position of the tape to count (not all
                tape drives support this feature).

     compress   If count is zero, disable compression.  Otherwise enable com-
                pression (not all tape drives support this feature).

     If a tape name is not specified, and the environment variable TAPE is not
     set, then mt uses the device /dev/nrst0.

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


ENVIRONMENT

     If the following environment variables exist, they are utilized by mt.

     TAPE        mt uses device filename given in the TAPE environment vari-
                 able if the tapename argument is not given.

     RCMD_CMD    mt will use RCMD_CMD rather than /usr/bin/rsh to invoke
                 rmt(8) on a remote machine.  The full path name must be spec-
                 ified.


FILES

     /dev/rst*                       Raw SCSI tape interface
     /dev/rmt*                       Raw magnetic tape interface
     src/sys/dev/scsipi/scsi_tape.h  List of SCSI-2 density codes


SEE ALSO

     dd(1), ioctl(2), mtio(4), environ(7)


BUGS

     The remote tape function is not implemented yet.


HISTORY

     The mt utility appeared in 4.3BSD.

NetBSD 1.4                       June 6, 1993                                2