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mt(1)									mt(1)



NAME

  mt - Magnetic	tape manipulating program

SYNOPSIS

  mt [-f tape_device] command [count]

  The mt program gives commands	to a magnetic tape drive.

OPTIONS

  -f tape_device
      This option specifies the	tape device to be manipulated.

  count	(integer)
      This option specifies the	number of times	that the operation is to be
      repeated.

DESCRIPTION

  If you do not	specify	a tape name with the -f	option,	the TAPE environment
  variable is used; if TAPE does not exist, mt uses the	/dev/ntape/tape0_d0
  device.  Note	that tape_device must refer to a raw (not block) tape device.
  By default, mt performs the requested	operation once.	 You can perform
  operations more than once using the count option.

  The following	commands are available:

  bsf Backspaces count files.

  bsr Backspaces count records.

  eof, weof
      Writes count End-of-File marks at	the current position on	the tape.

  fsf Forward spaces count files.

  fsr Forward spaces count records.

  load
      This option prepares a SCSI tape for loading into	the device.  Not all
      SCSI tape	drives support this command.

  offline, rewoffl
      Rewinds the tape and places the tape unit	offline	(count is ignored).

  online
      Bring a SCSI tape	to the ready state if a	tape is	in the tape path.
      Currently, this command is only supported	in the SCSI/CAM	tape driver.
      Not all SCSI tape	drives support this functionality.

  rewind
      Rewinds the tape (count is ignored).

  rdpos
      Sets the tape at the specified read position coordinates.	The data
      obtained when using the rdpos option can be used as an argument to the
      seek or seekds commands.

      Use the following	options	with the rdpos command:

      s	(the default)
	  The read position short format. This option requires a tape coordi-
	  nate argument	in the following syntax:
	       # mt -f /dev/ntape/tape1	rdpos s

	       READ POSITION short format
		       First block:	 3 (0x3)
		       Last block:	 0 (0x0)
		       Number of blocks: 0 (0x0)
		       Number of bytes:	 0 (0x0)

	  The preceding	example	provides the following information:

	  First	block
	      The block	address	associated with	the current logical position.

	  Last block
	      The block	address	associated with	the next block to be
	      transferred from the buffer to the medium.

	  Number of blocks
	      The number of data blocks	that have not been written to the
	      medium.

	  Number of bytes
	      The number of data bytes that have not been written to the
	      medium.

	  In addition to the information provided by the preceding example,
	  the rdpos s option may display additional messages. Availability of
	  these	additional messages depends on the capabilities	of the tape
	  drive	device.	 You will only see such	error messages if the tape
	  device is configured to detect the error state and to	display	the
	  appropriate message:

	  Position overflow error
	      An error has occurred and	the tape position cannot be returned.

	  Block	position unknown
	      An error has occurred as the device is incapable of reporting
	      block locations.

	  Byte count unknown
	      Number of	bytes in the buffer field does not represent the
	      actual number of bytes in	the buffer.

	  Block	count unknown
	      Number of	blocks in the buffer field does	not represent the
	      actual number of blocks in the buffer.

	  End of partition
	      The logical unit is positioned between early-warning and the
	      end of media (EOM).

	  Beginning of partition
	      The logical unit is at the beginning of media (BOM).

      l	(the default)
	  The read position long format. This option requires an argument in
	  the following	syntax:
	       # mt -f /dev/ntape/tape1	rdpos l
	       READ POSITION long format
		       File number:  0 (0x0)
		       Block number: 3 (0x3)

	  The following	information is returned:

	  File number
	      The number of file marks between BOM and current logical posi-
	      tion.

	  Block	number
	      The number of logical blocks between BOM and the current logi-
	      cal position.

	  In addition to the information provided by the preceding example,
	  the rdpos l option may display additional messages. Availability of
	  these	additional messages depends on the capabilities	of the tape
	  drive	device.	 You will only see such	error messages if the tape
	  device is configured to detect the error state and to	display	the
	  appropriate message:

	  Block	position unknown
	      An error has occurred as the device is incapable of reporting
	      block locations.

	  Mark position	unknown
	      File Number and Set Number are unknown

	  End of partition
	      The logical unit is positioned between early-warning and the
	      end of media (EOM).

	  Beginning of partition
	      The logical unit is at the beginning of media (BOM).

      d	  The read position short format, with device-specific addresses.
	  This option only works on certain devices and	requires a tape	coor-
	  dinate argument as for the s option.

	  The output will be the same format as	for the	s option, although
	  the device-specific data bytes may differ if the device supports
	  its own format. Not all devices support their	own format.  If	the d
	  option is not	supported by the device, the following	error message
	  will be displayed:
	       MTIOCRDPOS (dev_specific): I/O error



  seod
      Space to end of recorded data. Currently,	this command is	only sup-
      ported in	the SCSI/CAM tape driver.  Not all SCSI	tape drives support
      this functionality.

  seek
      Positions	a tape at the specified	coordinates. The output	of the rdpos
      command may be used as an	argument to this command. You can specify the
      value from the First block field when using the s	option.

  seekds
      Positions	a tape at the specified	coordinates. You can use the output
      from the rdpos command as	an argument, and the syntax is as for the
      seek command.

      Unlike the general seek command, the seekds command is device-specific.
      Some tape	devices	provide	a device-specific format for accessing the
      media position, which differs from the SCSI logical block	format
      defined by the SCSI standard.  The device-specific format	may provide a
      faster way of seeking to a particular position on	the tape.

  status
      Prints status information	about the tape unit.

  unload
      Prepares a SCSI tape for removal from the	device.	 Not all SCSI tape
      drives support this functionality.

  Only as many characters as are required to uniquely identify a command need
  to be	specified.

EXIT STATUS

  The mt command returns the following exit status:

  0 (Zero)
      Success.

  1   Command was unrecognized.

  2   Operation	failed.

FILES

  /dev/ntape/tape?_d?
      Raw magnetic tape	interface with no rewind when closed.

  /dev/tape/tape?_d?
      Raw magnetic tape	interface with rewind when closed.

SEE ALSO

  Commands:  dd(1)

  Functions:  ioctl(2)