MT(1)                   NetBSD General Commands 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
     default 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        Move forward count files from the beginning of the tape.  This
                is accomplished by a rewind followed by fsf 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.  (The count is ignored.)

     offline, rewoffl
                Rewind the tape and place the tape unit off-line.  Where sup-
                ported, this ejects the tape.  (The count is ignored.)

     status     Print status information about the tape unit.  (The count is
                ignored.)

     retension  Retensions the tape.  Not all tape drives support this fea-
                ture.  (The count is ignored.)

     erase      Erases the tape Not all tape drives support this feature.
                (The count is ignored.)

     eew        Enable or disable early warning EOM behaviour.  Set count to
                nonzero to enable, zero to disable.

     eom        Forward space to the end of recorded media.  (The count is
                ignored.)

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

     density, setdensity
                Set the tape density code to count as specified in the SCSI-3
                specification.  See the DENSITY CODES section for a list of
                codes for commonly used media types.

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

     rdhpos     Read the hardware block position of the tape.  Not all tape
                drives support this feature.  (The 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.

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

DENSITY CODES
     The SCSI-3 specification defines a number of density codes for various
     tape media, some of which are listed here.  Note that many tape drive
     vendors also define model-specific codes.

     Code    Format
     0       Device default
     1       1/2" 800 bpi
     2       1/2" 1600 bpi
     3       1/2" 6250 bpi
     4       QIC-11
     5       QIC-24
     15      QIC-120
     16      QIC-150
     17      QIC-320/525
     18      QIC-1320/1350
     19      DDS
     28      QIC-385M
     29      QIC-410M
     30      QIC-1000C
     31      QIC-2100C
     32      QIC-6GB
     33      QIC-20GB
     34      QIC-2GB
     35      QIC-875M
     36      DDS-2
     37      DDS-3
     38      DDS-4

ENVIRONMENT
     If the following environment variables exist, they are used 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 device
     /dev/rmt*  Raw magnetic tape device

SEE ALSO
     dd(1), ioctl(2), mtio(4), st(4), environ(7)

HISTORY
     The mt utility appeared in 4.3BSD.

NetBSD 5.0_STABLE                March 9, 2008               NetBSD 5.0_STABLE
