MT(1)

NAME
mt - magnetic tape control

SYNOPSIS
mt [-f device] [count]

DESCRIPTION
Mt is a user interface to the magnetic tape commands described in mtio(4). It allows one to space a tape forwards or backwards, write end of file markers, etc.

With the -f option a tape device can be named, otherwise the environment variable TAPE is used if set, otherwise the default device /dev/nrst4 is assumed. Standard input is used if the tape name is a dash (-). The count argument is used to tell how many blocks or files to space or how many file markers to write. It may be a C-style decimal, octal or hexadecimal constant, by default "1".

Command is the action to perform, it may be one of the following, or any unambiguous prefix (like st for status):

eof, weof
    Write count end-of-file markers.

fsf Forward space count file markers.

fsr Forward space count records. (The size of a record depends on the tape, and may even be variable, depending on the size of the writes.)

bsf Backwards space count files. The count may be zero to backspace to the start of the current file. (A tape device need not support backwards movement, or may be very slow doing it. Rewinding and forward spacing may be better.)

bsr Backwards space count records. The tape is positioned after the last block of the previous file if you hit a filemark when spacing backwards. The block count is set to -1 to indicate that the driver has no idea where it is on the previous file.

eom Forward space to the end of media.

rewind
    Rewind the tape.

offline, rewoffl
    Rewind and take offline. This may cause some drives to eject the tape.

status
    Shows the status of the drive, the sense key of the last SCSI error, current file number, current record number, residual count if the last command that encountered end-of-file, and the current block size.

retension
    Removes tape tension by winding and rewinding the tape completely.

erase
    Erases the tape completely and rewinds it.

density
    Sets the density code to read or write the tape to count. Density codes supported depend on the drive. This command need not be used if the drive senses the proper density on read and can only write one density.

blksize, blocksize
    Sets the block size used to read or write the tape to count. This command may be used to select a fixed block size for a variable block size tape. This will speed up I/O for small block sizes. Use a zero count to use variable sized blocks again.

ENVIRONMENT

TAPE
    Tape drive to use if set.

FILES

/dev/nrst4
    Default tape device.

SEE ALSO
mtio(4), st(4).

AUTHOR
Kees J. Bot (kjb@cs.vu.nl)