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.
ENVIRONMENT
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.
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
dd(1),
ioctl(2),
mtio(4),
st(4),
environ(7)
HISTORY
The
mt utility appeared in
4.3BSD.