mt - magnetic tape control
mt [-f device] [count]
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
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.
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
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.
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.
TAPE Tape drive to use if set.
/dev/nrst4 Default tape device.
Kees J. Bot (email@example.com)