MT(1)                                                       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 com-
       mands 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  abbre-
       viations  are  accepted.  Not all operations are available
       on all systems, or work on all types of tape drives.

       fsf    Forward space count files.  The tape is  positioned
              on the first block of the next file.

       fsfm   Forward  space count files.  The tape is positioned
              on the last block of the previous file.

       bsf    Backward space count files.  The tape is positioned
              on the last block of the previous file.

       bsfm   Backward space count files.  The tape is positioned
              on the first block of the next file.

       asf    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  file-
              marks.

       fsr    Forward space count records.

       bsr    Backward space count records.

       fss    (SCSI tapes) Forward space count setmarks.

       bss    (SCSI tapes) Backward space count setmarks.

       eod, seod
              Space  to end of valid data.  Used on streamer tape
              drives to append data to the logical and of tape.

       rewind Rewind the tape.

       offline, rewoffl
              Rewind the tape  and,  if  applicable,  unload  the
              tape.

       retension
              Rewind  the  tape,  then  wind it to the end of the
              reel, then rewind it again.

       weof, eof
              Write count EOF marks at current position.

       wset   (SCSI tapes) Write count setmarks at current  posi-
              tion (only SCSI tape).

       erase  Erase the tape.

       status Print status information about the tape unit.

       seek   (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.

       tell   (SCSI  tapes) Tell the current block on tape.  This
              operation is available on some Tandberg and Wangtek
              streamers and some SCSI-2 tape drives.

       setpartition
              (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.

       partseek
              (SCSI tapes) The tape  position  is  set  to  block
              count  in the partition given by the argument after
              count. The default partition is zero.

       mkpartition
              (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 ini-
              tiator-specified partition size and partition  sup-
              port must be enabled for the drive.

       load   (SCSI tapes) Load the tape into the drive.

       lock   (SCSI tapes) Lock the tape drive door.

       unlock (SCSI tapes) Unlock the tape drive door.

       setblk (SCSI  tapes)  Set  the  block size of the drive to
              count bytes per record.

       setdensity
              (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.

       densities
              (SCSI tapes) Write explanation of some common  den-
              sity codes to standard output.

       drvbuffer
              (SCSI tapes) Set the tape drive buffer code to num-
              ber.  The proper value for unbuffered operation  is
              zero and "normal" buffered operation one. The mean-
              ings of other values can be found in the drive doc-
              umentation  or, in case of a SCSI-2 drive, from the
              SCSI-2 standard.

       compression
              (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.

       stoptions
              (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  nec-
              essary, unambiguous abbreviations allowed):

              buffer-writes  buffered writes enabled

              async-writes   asynchronous writes enabled

              read-ahead     read-ahead for fixed block size

              debug          debugging (if compiled into driver)

              two-fms        write two filemarks when file closed

              fast-eod       space directly to eod (and lose file
                             number)

              auto-lock      automatically lock/unlock drive door

              def-writes     the block size and density  are  for
                             writes

              can-bsr        drive can space backwards well

              no-blklimits   drive  doesn't  support  read  block
                             limits

              can-partitions drive can handle partitioned tapes

              scsi2logical   seek and  tell  use  SCSI-2  logical
                             block  addresses  instead  of device
                             dependent addresses

              sysv           enable the System V semantics

       stsetoptions
              (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.

       stclearoptions
              (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.

       stwrthreshold
              (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.

       defblksize
              (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.

       defdensity
              (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.

       defdrvbuffer
              (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.

       defcompression
              (SCSI tapes) Set the default compression state. The
              value -1 disables the default compression. The com-
              pression state set  by  compression  overrides  the
              default  until a new tape is inserted. Allowed only
              for the superuser.

       sttimeout
              sets the normal timeout for the device.  The  value
              is  given  in  seconds.  Allowed only for the supe-
              ruser.

       stlongtimeout
              sets the long timeout for the device. The value  is
              given in seconds. Allowed only for the superuser.

       datcompression
              (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, com-
              pression is enabled.  The  command  uses  the  SCSI
              ioctl  to read and write the Data Compression Char-
              acteristics 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.Mak-
       isara@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
       st(4)

                           August 1998                          1