NAME
mt
—
magnetic tape manipulation
SYNOPSIS
mt |
[-f tapename]
command [count] |
DESCRIPTION
Themt
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.
cache
- Enable controller buffering.
nocache
- Disable controller buffering.
If a tape name is not specified, and the environment variable
TAPE
is not set, then mt
uses the device /dev/nrst0.
ENVIRONMENT
If the following environment variables exist, they are used by
mt
.
TAPE
mt
uses device filename given in theTAPE
environment variable if the tapename argument is not given.RCMD_CMD
mt
will useRCMD_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
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 |
SEE ALSO
HISTORY
The mt
utility appeared in
4.3BSD.