mt(1) mt(1)
mt - magnetic tape manipulating program
mt [ -f tapename ] command [ count ]
mt [ -t tapename ] command [ count ]
mt is used to give commands to the magnetic tape drives. By default, mt
performs the requested operation using /dev/nrtape. Normally the
operations are performed once. Some operations may be performed multiple
times by specifying count . For all others, count is ignored. count is
parsed with the strtol(3) library routine, which means that values with
leading 0's are taken as octal, those with leading 0x or 0x are taken to
be hex, and other's are taken to be decimal.
To use an alternate device, one of the options -f tapename or -t tapename
may be specified. If one of these options is not used, then mt will
check for an environment variable TAPE and use that, if set. Otherwise
the default device, /dev/nrtape is used.
The tapename field can also reference a remote tape device. A remote
tape device name has the form:
[user@]system:/dev/???
Where system is the remote system, /dev/??? is the particular drive on
the remote system (raw, rewinding, non-rewinding, etc.), and the optional
user is the login name to be used on the remote system (the default is
the current login name). The interface requires that the device portion
of the name start with /dev in order to be considered as a potential
remote device.
Note that when using a remote tape device, many commands may not be
supported by machines not running IRIX, and the meaning of some of the
status and position bits for the status command may differ.
If the rewind device is used, some commands are (long) null operations.
In particular, the feom and fsf commands will result in the tape being
positioned at BOT when the rewind device is used, rather than the
requested position.
The available commands are listed below. Only as many characters as are
required to uniquely identify a command need be specified. Note that not
all commands are implemented for all devices. For most of the commands
that accept a count, the default is 1, if not specified. Not all
commands are implemented by all devices or device drivers. Some may
return an error, others may return with no error, but not do anything
(such as attempting to retension a tape on a DAT drive).
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For those cases where the description seems unclear, it may be helpful to
refer to the comments in /usr/include/sys/mtio.h.
mt returns a 0 exit status when the operation was successful, a 1 if a
command was unrecognized, and a 2 if a operation failed. mt without any
arguments defaults to help.
weof Write count end-of-file marks at the current position on the tape.
wsetmk
Write count setmarks at the current position on the tape; currently
only supported for DAT, setmarks are intended for grouping tape
files into sets.
fsf Forward space count tape files. The resulting position is on the
EOT side of the filemark.
fsr Forward space count records (blocks).
bsf Backspace count tape files. The resulting position is on the BOT
side of the filemark.
bsr Backspace count records (blocks).
spsetmk
space count setmarks. The count is negative to space towards BOT,
and positive to space towards EOT.
rewind
Rewind the tape to BOT, or in the case of partitioned tapes, to the
beginning of the current partition (it does NOT change partitions).
sppart
Space to the given partition. Currently only supported for DAT
tape. The resulting position is the beginning of the partition, if
it exists. Only partitions 0 and 1 are supported for DDS format DAT
tapes. Partition 1 is the one closest to BOT. Once within a
partition, all other commands (except sppart or mkpart) apply to
that partition only, including rewind, erase, and feom.
mkpart
Create a partitioned tape. Currently only supported for DAT tape.
The argument specifies the size in megabytes of the partition
closest to BOT, which is known as partition 1. That part of the
tape is written and checked for errors. This is intended primarily
so that tape directories may be written at the beginning of the tape
with no possibility of overwriting the primary data on the tape. An
argument of 0 creates a single partition tape again.
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feom Forward space to end of recorded data. This allows appending new
tape files to a tape that already contains data. For partitioned
tapes, positions to the end of recorded data in the current
partition.
offline
Rewind and unload the tape from the drives heads, allowing removal
of the tape. The tape is not ejected for most drive types.
Use the unload option to force ejection (for drives that support
ejection or similar behavior; not all drives do).
unload
Inform the drive it is OK for the tape to be removed. This is
meaningful only for drives such as the 8mm drive that enable and
disable the eject button under software control. Some drives will
otherwise not allow tape removal if the tape has not been previously
rewound. If the drive supports it, the tape is ejected.
erase
Erase from current position to EOT. This can be very slow for some
tape drives (up to 2 hours for 8mm tape drives with 2.3Gb capacity).
Note that for QIC drives, all tracks are erased simultaneously (QIC
writes in serpentine fashion, with anywhere from 9-30 tracks,
currently). This means that one should not expect to be able to
erase just the "tail end" of a QIC tape, without losing most, if not
all, of the data on the tape. The erase function is not supported
on DAT drives when they are in audio mode. The erase function is
not supported on Ampex DST drives.
exist
Exit with status 0 if the drive exists, otherwise non-zero; this is
primarily for use in scripts.
recerron
Enable soft error reporting for drives that are very verbose about
them, such as Cipher 540S; this persists until explicitly turned
off. The default is recerroff.
recerroff
Disable soft error reporting for drives that are very verbose about
them, such as Cipher 540S. This is the default behavior.
sili Suppress illegal length indicator (this occurs on tapes like the 8mm
tape drive when a request is made to read fewer bytes than a block
was written with, when in variable block mode). The default is to
return a short count, when set, no short count will be returned, and
the rest of the data in the block will be skipped. This is off by
default. This persists until explicitly turned off or the tape is
changed.
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eili Reverses the effect of sili (returns to default).
audio
Set the tape device to be in audio mode if the argument is non-zero,
or in data mode (the default) if it is zero. This is currently
supported only for DAT tapes, and allows the transfer of digital
audio music to and from the drive over the SCSI bus. In this mode,
many of the data commands, such as weof are not allowed. The
variable blocksize tape device should always be used when doing i/o
in audio mode. The other tape parameters, such as recording
frequency, program number, and so on must be transferred to the
drive as part of the data stream. In addition, rewinds and seeks
return immediately in audio mode, and further opens will block until
they are complete. See the tps(7m) manual page for more
information.
seek Seek to the block given as the argument. For multiple partition
tapes, this is relative to start of partition, otherwise to BOT.
When in audio mode, this specifies the program number (0 - 799)
rather than a block number. The argument block number should be
provided as a SCSI logical block number for SCSI tape drives, except
for the STK drives, for which the argument is the block number in
vendor unique format.
status
Print status information about the tape unit. It is not necessary
to have media physically loaded to obtain status. The position
information from the mt_dposn field of the structure returned by the
MTIOCGET is printed for all drive types. For tps (SCSI) drives,
status information from the mt_erreg is also printed, which gives
addition information about tape status. The current block position
provided is the SCSI logical block address in all cases, except for
the STK drives, which report the position in vendor unique block
number format. The numeric field "Status" contains the mt_dposn
bits in the low 16 bits, and the mt_erreg values in the upper 16
bits. These bits are defined in /usr/include/sys/tpsc.h.
The meaning of the bits that are driver specific may vary from
release to release, and are primarily useful when reporting tape
problems to the customer support organization.
blksize
Print the recommended block size for io, which is used by tar, cpio,
bru, etc. A tape cartridge need not be physically loaded to obtain
default block size, except that current block sizes will not be
accurate in this case. The maximum, minimum, and current blocksizes
are also reported; they may all be the same if the drive does not
support variable block sizes.
setblksz
Sets the block size to be used when in fixed blocksize mode. Most
drives that support variable sized blocks also support use of
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different sized blocks in the fixed block mode. For example, this
could be used to read 8 mm tapes written with a fixed block size of
512 bytes, rather than 1024, while still reading more than 512 bytes
per system call. If this was not done, tape errors would occur.
This size remains set until the next tape change, or until the drive
is used in variable block mode.
retension
Retension the tape in the drive. This may be a null operation on
some drives, such as DAT.
reserve
Issues a request to reserve a tape device. This operation is
persistent and remains until explicitly removed with a release
command. The SCSI tape interface (TPSC) uses the SCSI reserve
command. Tape support (TS) uses the SCSI persistent reserve out
command if it is supported by the device; otherwise, the SCSI
reserve command is used. This operation requires CAP_DEVICE_MGT
capability.
release
Issues a release request to a tape device. The SCSI tape interface
(TPSC) uses the SCSI release command. Tape support (TS) uses the
SCSI persistent reserve out command if it is supported by the
device; otherwise, the SCSI release command is used. This operation
requires CAP_DEVICE_MGT capability.
preempt
Preempts reservations. This action should only be done in error
recovery situations. Tape support (TS) uses the preempt service
action of the SCSI persistent reserve out command to preempt
reservations made from another host. Not all devices support the
persistent reserve out command. This operation requires
CAP_DEVICE_MGT capability.
clear
Clears reservations. This action should only be done in error
recovery situations. Tape support (TS) uses the clear service
action of the SCSI persistent reserve in command to clear
reservations made from another host. Not all devices support the
persistent reserve out command. This operation requires
CAP_DEVICE_MGT capability.
prsv Shows the persistent reservation key of the device and the active
reservation if one exists. Tape support (TS) uses the prsv command
on devices that support the SCSI persistent reserve in command. The
persistent reservation key that is used by TS is the first 8 bytes
of the hostname.
help Print a summary of the available options.
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/dev/nrtape default (no rewind) tape device
rmt(1M), rmtops(3), mtio(7), tps(7m).
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