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 for-
wards 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. 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 fol-
lowing, 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 sup-
port 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 previ-
ous 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 den-
sity 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)