magnetic tape and removable media
mt utility sends commands to a
magnetic tape drive. By default,
mt performs the
requested operation once. Operations may be performed multiple times by
specifying count. Note that
device must reference a raw (not block) tape device.
If device is of the form “host:device”
mt writes to
the named tape device on the remote host using
eject is simply an alias for
mt, with the
eject may also be used to eject other
types of removable media.
The options for
mt are as follows:
- Operate on the device specified.
The options for
eject are as follows:
- Insert the device instead of ejecting. For the cd(4) driver, this requests that the tray be closed.
The available commands are listed below. Only as many characters as are required to uniquely identify a command need be specified.
- Write count end-of-file marks at the current position on the tape.
- Forward space count files.
- Forward space count records.
- Back space count files.
- Back space count records.
- Rewind the tape (count
- Rewind the tape and place the tape unit off-line
is ignored). On non-tape removable media, the
offlinecommand causes the media to be ejected when the last operation on it closes (i.e., the filesystem is unmounted).
- Print status information about the tape unit.
- Retension the tape (if this operation is supported by the tape unit).
- Erase the tape (if this operation is supported by the tape unit).
- Forward space to the end of the media.
- Set the tape blocksize to count bytes.
- Set the tape density code to count as specified in the SCSI2 specification.
If a tape name is not specified, and the environment variable
TAPE does not exist,
the device /dev/rst0. The
TAPE variable is ignored by
If the following environment variable exists, it is utilized by
TAPEenvironment variable if the argument device is not given.
- raw SCSI tape interface
- raw magnetic tape interface
- list of SCSI2 density codes
mt returns a 0 exit status when the
operation(s) were successful, 1 if the command was unrecognized, and 2 if an
Eject the first CD device. This will work even if there is no CD in the drive:
$ eject /dev/rcd0c
cdio(1), chio(1), dd(1), ioctl(2), mtio(4)
mt utility appeared in
Version 2 AT&T UNIX.