copytape - duplicate magtapes
copytape duplicates magtapes. It is intended for duplication of bootable
or other non-file-structured (non-tar-structured) magtapes on systems with
only one tape drive. copytape is blissfully ignorant of tape formats.
It merely makes a bit-for-bit copy of its input.
In normal use, copytape would be run twice. First, a boot
tape is copied to an intermediate disk file. The file is in a special format
that preserves the record boundaries and tape marks. On the second run,
copytape reads this file and generates a new tape. The second step
may be repeated if multiple copies are required. The typical process would
look like this:
tutorial% copytape /dev/rmt8 tape.tmp
tutorial% copytape tape.tmp /dev/rmt8
tutorial% rm tape.tmp
copytape copies from the standard input to the standard
output, unless input and output arguments are provided. It will
automatically determine whether its input and output are physical tapes, or
data files. Data files are encoded in a special (human-readable) format.
Since copytape will automatically determine what sort of
thing its input and output are, a twin-drive system can duplicate a tape in
one pass. The command would be
tutorial% copytape /dev/rmt8 /dev/rmt9
ansitape(1), dd(1), tar(1), mtio(4), copytape(5)
David S. Hayes, Site Manager, US Army Artificial Intelligence Center. Originally
developed September 1984 at Rensselaer Polytechnic Institute, Troy, New York.
Revised July 1986. This software is in the public domain.
copytape treats two successive file marks as logical end-of-tape.
- Skip tape marks. The specified number of tape marks are skipped on the
input tape, before the copy begins. By default, nothing is skipped,
resulting in a copy of the complete input tape. Multiple tar(1) and
dump(1) archives on a single tape are normally separated by a single tape
mark. On ANSI or IBM labelled tapes, each file has three associated tape
marks. Count carefully.
- Limit. Only nnn files (data followed by a tape mark), at most, are copied.
This can be used to terminate a copy early. If the skip option is also
specified, the files skipped do not count against the limit.
- From tape. The input is treated as though it were a physical tape, even if
it is a data file. This option can be used to copy block-structured device
files other than magtapes.
- To tape. The output is treated as though it were a physical tape, even if
it is a data file. Normally, data files mark physical tape blocks with a
(human-readable) header describing the block. If the -t option is used
when the output is actually a disk file, these headers will not be
written. This will extract all the information from the tape, but
copytape will not be able to duplicate the original tape based on
the resulting data file.
- Verbose. copytape does not normally produce any output on the
control terminal. The verbose option will identify the input and output
files, tell whether they are physical tapes or data files, and announce
the size of each block copied. This can produce a lot of output on even
relatively short tapes. It is intended mostly for diagnostic work.
The intermediate data file can consume huge amounts of disk space.
A 2400-foot reel at 6250-bpi can burn 140 megabytes. This is not strictly
speaking a bug, but users should be aware of the possibility. Check disk
space with df(1) before starting copytape. Caveat Emptor!
A 256K buffer is used internally. This limits the maximum block
size of the input tape.