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 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 vari­
       able  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.

       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. Posi­
              tioning is done by first rewinding the tape and then spacing for­
              ward over count filemarks.

       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 position (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 mul­
              tiple partitions.

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

       mkpartition
              (SCSI tapes) Format the tape with one (count is zero) or two par­
              titions  (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  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  density  codes  to
              standard output.

       drvbuffer
              (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.

       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 neces­
              sary, 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  stop­
              tions.  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 stop­
              tions.  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  supe­
              ruser.

       defdrvbuffer
              (SCSI tapes) Set the default drive buffer code. The value -1 dis­
              ables 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 dis­
              ables  the default compression. The compression state set by com­
              pression 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 superuser.

       stlongtimeout
              sets the long timeout for the device. The value is given in  sec­
              onds. 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,  compres­
              sion  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  com­
              mand  is  not  currently included in the default configuration of
              mt.

       mt exits with a status of 0 if the operation succeeded, 1 if the  opera­
       tion or device name given was invalid, or 2 if the operation failed.

AUTHOR
       The program is written by Kai Makisara .

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