A/UX® System Administrator's Reference Sections 1M, 7, and 8

tc(7) tc(7)
The tcb(l) program helps overcome the fixed-block-size problem
when it is used to read from the tape or when it is used just before
a write to the tape.
Each read or wri te call reads or writes the next record on the
tape. When writing, the record size returned is the same length as
the block size given. When reading, the record size returned is the
actual number of bytes read, which can be no greater than the
buffer size; if the record is too long, an error is indicated.
For the tc device driver, the ioctls and data structures associated
with the mtio(7) generic tape interface are supported, including
MTIOCGET and MTIOCTOP. The MTIOCGET ioctl returns the
driver's notion of current file and block number information in
mt fileno and mt blkno. The rot dsreg field contains the
logIcal block numbef where the last I/O operation occurred.
Though this generally matches mt blkno, they are both returned
for testing purposes. -
The mt _ erreg field always contains the current driver version.
The number is a short integer, which is expressed as x. mn (for example,
3.24). The version is encoded as
(100 * x) + (10 *m) + n
For this example, the value would be decimal 324.
The mt resid field contains the number of usable blocks on the
currently loaded cartridge. If this field is 0, the cartridge is not
formatted.
FILES
/dev/rmt/tc [0-7]
/dev/rmt/tc[0-7]n
SEE ALSO
mt(1), tar(1), tcb(1), tp(l), mtio(7).
Rewind on close
No rewind on close
DIAGNOSTICS
If an unformatted cartridge is loaded and the device is opened for
read only, EINVAL is returned
BUGS
The tapemark format does not conform to any known standard because
such standards are nonexistent. When end-of-file is encountered
at a simulated tapemark, the tapemark record is transferred
to the user's buffer, even though the return from read(2)
(correctly) does not include the tapemark bytes. A O-byte count is
February,1990
Revision C
2