tapecntl sends the optional commands to the tape device
driver sub-device /dev/rmt/ntape.
Error messages are written to standard error.
device is the tape
device, and defaults to /dev/rmt/ntape1 if not specified.
Not all options are supported by all tape devices
or all tape device drivers.
Options
tapecntl takes the following options:
-C
Read compression characteristics.
-a
Position the tape to the end of data (EOD) mark.
This option is valid only for SCSI tape devices.
-b
Read block length limits from the tape device and display them.
-c [n]
Set compression characteristics where n is:
value of n
compression
decompression
0
off
off
1
on
off
2
off
on
3
on
on
NOTE:
This option only works with SCSI drives that
support data compression and decompression.
-e
Erase the tape.
The erase bar is activated while moving the tape from
beginning to end, erasing all data tracks in a single
pass over the tape.
-l
Load the tape media and position the tape at the
beginning of tape (BOT) mark.
-r
Reset the tape device, initializing the tape controller registers
and positioning the tape at the beginning of tape (BOT) mark.
-t
Retension the tape, moving the tape from beginning to end
and back,
thereby repacking the tape
with the proper tension across its length.
-u
Unload the tape media from the tape device.
Depending on the device, unloading
may include ejecting the cartridge.
-v
Set the tape device to read and write variable length blocks.
This option works only on devices that support variable
length blocks.
-w
Rewind the tape, moving the tape to the BOT mark.
-d [n]
Set the tape density where n is
the numeric density code as defined in the SCSI-2
specification.
This option works only with SCSI drives.
The number specified must be in decimal.
Common density codes include:
0
the default value for the device, meaning autodetect
4
QIC-11
5
QIC-24;
15
QIC-120
16
QIC-150
Zero is the recommended value.
For DAT devices, 0 and 13 both denote the DDS format and
are the only valid density codes.
-f [n]
Set the tape device to read and write in fixed
length blocks of n bytes.
Individual devices have specific limitations and you
should set this parameter only to a value supported
by the device.
-p [n]
Position tape past the end of file (EOF) mark n,
where n is an integer, positive or negative,
representing the number of EOF marks to move forward
or backward.
A positive integer moves the tape forward relative to its
current position, to a point just after the specified EOF mark.
A negative integer moves the tape backward in the same
manner, to a point on the tape just before the specified EOF mark.
So, for example, using -p 2 will move the tape to
the beginning of the third record; using -p -1
will move the tape back past the previous file mark,
putting the tape at the end of the record.
For this reason, backward positioning cannot move to the
beginning of a record, and because backward positioning
is slow, rewinding and moving forward to the needed record
is the recommended approach.
NOTE:
Backward positioning is not available on all devices.
A positioning value of zero is ignored.
Illegal or out-of-range values
will leave the tape positioned at the
last valid EOF mark.
Options can be used individually or strung together.
The default mode for I/O from any magnetic tape, such
as QICtape, 9-track, or DAT is fixed-length blocks
which are 512 bytes long.
Devices
Node names for device and their corresponding functionality are:
ctape*
Does not retension tape at open.
Rewinds and does not unload tape at close.
nrtape*
Retensions tape at open.
Does not rewind and does not unload tape at close.
ntape*
Does not retension tape at open.
Does not rewind and does not unload tape at close.
rtape*
Retensions tape at open.
Rewinds and does not unload tape at close.
utape*
Does not retension tape at open.
Rewinds and unloads tape at close.
Files
/dev/rmt/ctape
/dev/rmt/nrtape
/dev/rmt/ntape
/dev/rmt/rtape
/dev/rmt/utape
/usr/bin/tapecntl
Exit codes
Exit codes for tapecntl
and their meanings are as follows:
1
Device function could not initiate properly due to
misconnected cables or poorly inserted tape cartridge.
2
Device function failed to complete properly due to
unrecoverable error condition, either in the command setup or
due to mechanical failure.
3
Device function failed due to the cartridge being write
protected or to the lack of written data on the tape.
4
Device /dev/rmt/ntape or /dev/rmt/ctape
failed to open properly due to already being opened
or claimed by another process.
Notices
Using variable-length block mode when
writing magnetic tapes is discouraged because it may not
work correctly in releases before SVR4.2 MP. Magnetic tape should
always be written in fixed-length block mode, even though you are
free to change the default fixed-block length from 512 bytes to any
other fixed-block mode the tape drive supports.
The default mode for I/O from any magnetic tape
(QICtape, 9-track, DAT) is fixed-length blocks 512 bytes long.
