MT(1)

NAME
mt - magnetic tape manipulating program

SYNOPSIS
mt [-f tapename] command [count]

DESCRIPTION
mt ~ is used to give 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 tapename must reference a raw (not block) tape device.

The available commands are listed below. Only as many characters as are required to uniquely identify a command need be specified.

weof
    Write count end-of-file marks at the current position on the tape.

fsf Forward space count files.

fsr Forward space count records.

bsf Back space count files.

bsr Back space count records.

rewind
    Rewind the tape (Count is ignored).

offline, rewoffl
    Rewind the tape and place the tape unit off-line (Count is ignored).

erase
    Erase the tape (Count is ignored).

retension
    Re-tension the tape (one full wind forth and back, Count is ignored).

status
    Print status information about the tape unit.

blocksize
    Set the block size for the tape unit. Zero means variable-length blocks.

density
    Set the density for the tape unit. For the density codes, see below. The density value could be given either numerically, or as a string, corresponding to the “Reference” field. If the string is abbreviated, it will be resolved in the order shown in the table, and the first matching entry will be used. If the given string and the resulting canonical density name do not match exactly, an informational message is printed about what the given string has been taken for.

eom Forward space to end of recorded medium (Count is ignored).

comp
    Set compression mode. (Not yet implemented.)

If a tape name is not specified, and the environment variable TAPE does not exist; mt uses the device /dev/nrst0.

mt ~ returns a 0 exit status when the operation(s) were successful, 1 if the command was unrecognized, and 2 if an operation failed.

The different density codes are as follows:

    0x0 default for device
    0xE reserved for ECMA

    Value Tracks Density(bpi) Code Type  Reference     Note
    0x1     9       800       NRZI  R    X3.22-1983    2
    0x2     9      1600       PE    R    X3.39-1986    2
    0x3     9      6250       GCR   R    X3.54-1986    2
    0x5    4/9     8000       GCR   C    X3.136-1986   1
    0x6     9      3200       PE    R    X3.157-1987   2
    0x7     4      6400       IMFM  C    X3.116-1986   1
    0x8     4      8000       GCR   CS   X3.158-1986   1
    0x9    18     37871       GCR   C    X3B5/87-099   2
    0xA    22      6667       MFM   C    X3B5/86-199   1
    0xB     4      1600       PE    C    X3.56-1986    1
    0xC    24     12690       GCR   C    HI-TC1        1,5
    0xD    24     25380       GCR   C    HI-TC2        1,5
    0xF    15     10000       GCR   C    QIC-120       1,5
    0x10   18     10000       GCR   C    QIC-150       1,5
    0x11   26     16000       GCR   C    QIC-320(525?) 1,5
    0x12   30     51667       RLL   C    QIC-1350      1,5
    0x13    1     61000       DDS   CS   X3B5/88-185A  4
    0x14    1     43245       RLL   CS   X3.202-1991   4
    0x15    1     45434       RLL   CS   ECMA TC17     4
    0x16   48     10000       MFM   C    X3.193-1990   1
    0x17   48     42500       MFM   C    X3B5/91-174   1

where Code means:

    NRZI	Non Return to Zero, change on ones
    GCR	Group Code Recording
    PE	Phase Encoded
    IMFM	Inverted Modified Frequency Modulation
    MFM	Modified Frequency Modulation
    DDS	Dat Data Storage
    RLL	Run Length Encoding

where Type means:

    R	Reel-to-Reel
    C	Cartridge
    CS	cassette

where Notes means:

    1	Serial Recorded
    2	Parallel Recorded
    3	Old format know as QIC-11
    4	Helical Scan
    5	Not ANSI standard, rather industry standard.

ENVIRONMENT
If the following environment variable exists, it is utilized by mt.

TAPE
    mt ~ checks the TAPE environment variable if the argument tapename is not given.

FILES
/dev/rwt*
    Raw magnetic tape interface
/dev/*st[0-9]*
    SCSI magnetic tape interface

SEE ALSO
st(4), dd(1), ioctl(2), environ(7)

HISTORY
The mt command appeared in 4.3BSD. Extensions regarding the st(4) driver appeared in 386BSD 0.1 as a separate st(1) command, and have been merged into the mt command in FreeBSD 2.1.