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.