mt
—
magnetic tape manipulation
mt |
[-f tapename]
command [count] |
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.
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.
If the following environment variables exist, they are used by
mt
.
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.
- /dev/rst*
- Raw SCSI tape device
- /dev/rmt*
- Raw magnetic tape device
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 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 |
The mt
utility appeared in
4.3BSD.