MT (1)
control magnetic tape drive operation
SYNOPSIS
mt
[-h] [-f device] operation [count] [arguments...]
DESCRIPTION
This manual page documents the tape control program
mt .
mt
performs the given
operation ,
which must be one of the tape operations listed below, on a tape
drive. The commands can also be listed by running the program with the
-h
option. The version of mt is printed with the
-v
option. The path of the tape device to operate on can be given with
the
-f
or
-t
option. If neither of those options is given, and the environment
variable
TAPE
is set, it is used. Otherwise, a default device defined in the file
/usr/include/sys/mtio.h
is used.
Some operations optionally take an argument or repeat count, which can be given
after the operation name and defaults to 1.
The available operations are listed below. Unique abbreviations are
accepted. Not all operations are available on all systems, or work on
all types of tape drives.
Forward space
count
files.
The tape is positioned on the first block of the next file.
Forward space
count
files.
The tape is positioned on the last block of the previous file.
Backward space
count
files.
The tape is positioned on the last block of the previous file.
Backward space
count
files.
The tape is positioned on the first block of the next file.
The tape is positioned at the beginning of the
count
file. Positioning is done by first rewinding the tape and then spacing
forward over
count
filemarks.
Forward space
count
records.
Backward space
count
records.
(SCSI tapes) Forward space
count
setmarks.
(SCSI tapes) Backward space
count
setmarks.
Space to end of valid data. Used on streamer tape
drives to append data to the logical and of tape.
Rewind the tape and, if applicable, unload the tape.
Rewind the tape, then wind it to the end of the reel,
then rewind it again.
Write
count
EOF marks at current position.
(SCSI tapes) Write
count
setmarks at current position (only SCSI tape).
Print status information about the tape unit.
(SCSI tapes) Seek to the
count
block on the tape. This operation is available on some
Tandberg and Wangtek streamers and some SCSI-2 tape drives. The block
address should be obtained from a
tell
call earlier.
(SCSI tapes) Tell the current block on tape. This operation is available on some
Tandberg and Wangtek streamers and some SCSI-2 tape drives.
(SCSI tapes) Switch to the partition determined by
count.
The default data partition of the tape is numbered zero. Switching
partition is available only if enabled for the device, the device
supports multiple partitions, and the tape is formatted with multiple
partitions.
(SCSI tapes) The tape position is set to block
count
in the partition given by the argument after count. The default
partition is zero.
(SCSI tapes) Format the tape with one (count is zero) or two partitions
(count gives the size of the second partition in megabytes). The tape
drive must be able to format partitioned tapes with
initiator-specified partition size and partition support
must be enabled for the drive.
(SCSI tapes) Load the tape into the drive.
(SCSI tapes) Lock the tape drive door.
(SCSI tapes) Unlock the tape drive door.
(SCSI tapes) Set the block size of the drive to
count
bytes per record.
(SCSI tapes) Set the tape density code to
count.
The proper codes to use with each drive should be looked up from the
drive documentation.
(SCSI tapes) Write explanation of some common density codes to
standard output.
(SCSI tapes) Set the tape drive buffer code to
number.
The proper value for unbuffered operation is zero and "normal" buffered
operation one. The meanings of other values can be found in the drive
documentation or, in case of a SCSI-2 drive, from the SCSI-2 standard.
(SCSI tapes) The compression within the drive can be switched on or
off using the MTCOMPRESSION ioctl. Note that this method is not
supported by all drives implementing compression. For instance, the
Exabyte 8 mm drives use density codes to select compression.
(SCSI tapes) Set the driver options bits for the device to the defined
values. Allowed only for the superuser. The bits can be set
either by oring the option bits from the file /usr/include/linux/mtio.h to
count,
or by using the following keywords (as many keywords can be used on
the same line as necessary, unambiguous abbreviations allowed):
asynchronous writes enabled
read-ahead for fixed block size
debugging (if compiled into driver)
write two filemarks when file closed
space directly to eod (and lose file number)
automatically lock/unlock drive door
the block size and density are for writes
drive can space backwards well
drive doesn't support read block limits
drive can handle partitioned tapes
seek and tell use SCSI-2 logical block addresses instead of device
dependent addresses
enable the System V semantics
(SCSI tapes) Set selected driver options bits. The methods to specify
the bits to set are given above in description of stoptions.
Allowed only for the superuser.
(SCSI tapes) Clear selected driver option bits. The methods to specify
the bits to clear are given above in description of stoptions.
Allowed only for the superuser.
(SCSI tapes) The write threshold for the tape device is set to
count
kilobytes. The value must be smaller than or equal to the driver
buffer size. Allowed only for the superuser.
(SCSI tapes) Set the default block size of the device to
count
bytes. The value -1 disables the default block size.
The block size set by
setblk
overrides the default until a new tape is inserted.
Allowed only for the superuser.
(SCSI tapes) Set the default density code. The value -1 disables the
default density. The density set by
setdensity
overrides the default until a new tape is inserted. Allowed only for the
superuser.
(SCSI tapes) Set the default drive buffer code. The value -1 disables the
default drive buffer code. The drive buffer code set by
drvbuffer
overrides the default until a new tape is inserted. Allowed only for the
superuser.
(SCSI tapes) Set the default compression state. The value -1 disables the
default compression. The compression state set by
compression
overrides the default until a new tape is inserted. Allowed only for the
superuser.
sets the normal timeout for the device. The value is given in
seconds. Allowed only for the superuser.
sets the long timeout for the device. The value is given in
seconds. Allowed only for the superuser.
(some SCSI-2 tapes) Inquire or set the compression status
(on/off) using SCSI commands sent by mt. If the
count
is omitted the compression status is printed. If the
count
is zero or "off", compression is disabled. If the
count
is anything else, compression is enabled. The command uses the SCSI ioctl to
read and write the Data Compression Characteristics mode page
(15). ONLY ROOT CAN USE THIS COMMAND. The compression can be
controlled with the mt command
compression
with kernels above 1.3.84. This command is not currently included in
the default configuration of mt.
mt
exits with a status of 0 if the operation succeeded, 1 if the
operation or device name given was invalid, or 2 if the operation
failed.
AUTHOR
The program is written by Kai Makisara <Kai.Makisara@metla.fi>.
COPYRIGHT
The program and the manual page are copyrighted by Kai Makisara, 1998.
They can be distributed according to the GNU Copyleft.
SEE ALSO
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