March 9, 2008 MT 1

### NAME

mt - magnetic tape manipulation

### SYNOPSIS

mt [-f tapename] command [count]

### DESCRIPTION

The mt program 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. If tapename is of the form "host:tapename, or "user@host:tapename, mt writes to the named tape device on the remote host using rmt(8).

The rmt(8) process on the remote host is typically initiated via rsh(1), although an alternate method such as ssh(1) can be specified via the ```RCMD_CMD` environment variable.

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

asf
  Move forward count files from the beginning of the tape. This is accomplished by a rewind followed by fsf count.

eof, 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. (The count is ignored.)

offline, rewoffl
  Rewind the tape and place the tape unit off-line. Where supported, this ejects the tape. (The count is ignored.)

status
  Print status information about the tape unit. (The count is ignored.)

retension
  Retensions the tape. Not all tape drives support this feature. (The count is ignored.)

erase
  Erases the tape Not all tape drives support this feature. (The count is ignored.)

eew
  Enable or disable early warning EOM behaviour. Set count to nonzero to enable, zero to disable.

eom
  Forward space to the end of recorded media. (The count is ignored.)

blocksize, setblk
  Set the tape blocksize to count bytes. A count of zero sets variable blocksize.

density, setdensity
  Set the tape density code to count as specified in the SCSI-3 specification. See the DENSITY CODES section for a list of codes for commonly used media types.

rdspos
  Read the logical block position of the tape. Not all tape drives support this feature. (The count is ignored.)

rdhpos
  Read the hardware block position of the tape. Not all tape drives support this feature. (The count is ignored.)

setspos
  Set the logical block position of the tape to count. Not all tape drives support this feature.

sethpos
  Set the hardware block position of the tape to count. Not all tape drives support this feature.

compress
  If count is zero, disable compression. Otherwise enable compression. Not all tape drives support this feature.

If a tape name is not specified, and the environment variable ```TAPE` is not set, then mt uses the device ```/dev/nrst0`.

### EXIT STATUS

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

### DENSITY CODES

The SCSI-3 specification defines a number of density codes for various tape media, some of which are listed here. Note that many tape drive vendors also define model-specific codes.

Code Format
```0` | `Device` `default`
```1` | `1/2"``800` `bpi`
```2` | `1/2"``1600` `bpi`
```3` | `1/2"``6250` `bpi`
```4` | `QIC-11`
```5` | `QIC-24`
```15` | `QIC-120`
```16` | `QIC-150`
```17` | `QIC-320/525`
```18` | `QIC-1320/1350`
```19` | `DDS`
```28` | `QIC-385M`
```29` | `QIC-410M`
```30` | `QIC-1000C`
```31` | `QIC-2100C`
```32` | `QIC-6GB`
```33` | `QIC-20GB`
```34` | `QIC-2GB`
```35` | `QIC-875M`
```36` | `DDS-2`
```37` | `DDS-3`
```38` | `DDS-4`

### ENVIRONMENT

If the following environment variables exist, they are used by .

```TAPE`
  mt uses device filename given in the ```TAPE` environment variable if the tapename argument is not given.

```RCMD_CMD`
  mt will use ```RCMD_CMD` rather than ```/usr/bin/rsh` to invoke rmt(8) on a remote machine. The full path name must be specified.

### FILES

```/dev/rst*`
  Raw SCSI tape device
```/dev/rmt*`
  Raw magnetic tape device

### SEE ALSO

dd(1), ioctl(2), mtio(4), st(4), environ(7)

### HISTORY

The mt utility appeared in 4.3BSD.