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 performed 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 ignored).

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

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 compression (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.

TAPE
    mt uses device filename given in the TAPE environment variable 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 specified.

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.