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MT(1) General Commands Manual MT(1)

NAME

mt - 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.

Some operations optionally take an argument or repeat count, which can be given after the operation name and defaults to 1. The postfix k , M , or G can be used to give counts in units of 1024, 1024 * 1024, or 1024 * 1024 * 1024, respectively.

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, then backward space one record. This leaves the tape positioned at the last block of the file that is count - 1 files past the current file.
Backward space count files. The tape is positioned on the last block of the previous file.
Backward space count files, then forward space one record. This leaves the tape positioned at the first block of the file that is count - 1 files before the current 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 end of tape.
Rewind the 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).
Erase the tape. Note that this is a long erase, which on modern (high-capacity) tapes can take many hours, and which usually can't be aborted.
Print status information about the tape unit. (If the density code is "no translation" in the status output, this does not affect working of the tape drive.)
(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). If the count is positive, it specifies the size of partition 1. From kernel version 4.6, if the count is negative, it specifies the size of partition 0. With older kernels, a negative argument formats the tape with one partition. 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) Send the load command to the tape drive. The drives usually load the tape when a new cartridge is inserted. The argument count can usually be omitted. Some HP changers load tape n if the count 10000 + n is given (a special function in the Linux st driver).
(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 the 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):
buffered writes enabled
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)
don't wait until rewind, etc. complete
automatically lock/unlock drive door
the block size and density are for writes
drive can space backwards as 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
Set the SILI bit is when reading in variable block mode. This may speed up reading blocks shorter than the read byte count. Set this option only if you know that the drive supports SILI and the HBA reliably returns transfer residual byte counts. Requires kernel version >= 2.6.26.
enable the System V semantics
(SCSI tapes) Set selected driver options bits. The methods to specify the bits to set are given above in the 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) Print the currently enabled options for the device. Requires kernel version >= 2.6.26 and sysfs must be mounted at /sys.
(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.
set the cleaning request interpretation parameters.

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.

OPTIONS

Print a usage message on standard output and exit successfully.
Print version of mt.
The path of the tape device on which to operate. 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 (note that the actual path to mtio.h can vary per architecture and/or distribution).

NOTES

The argument of mkpartition specifies the size of the partition in megabytes. If you add a postfix, it applies to this definition. For example, argument 1G means 1 giga megabytes, which probably is not what the user is anticipating.

AUTHOR

The program is written by Kai Makisara <Kai.Makisara@kolumbus.fi>, and is currently maintained by Iustin Pop <iustin@k1024.org>.

COPYRIGHT

The program and the manual page are copyrighted by Kai Makisara, 1998-2008. They can be distributed according to the GNU Copyleft.

BUGS

Please report bugs to <https://github.com/iustin/mt-st>.

SEE ALSO

st(4)

April 2008