NAME

copytape - duplicate magtapes

SYNOPSIS

copytape

DESCRIPTION

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

OPTIONS

-snnn: 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.
-lnnn: 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.
-f: 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.
-t: 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.
-v: 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.

FILES

/dev/rmt*

AUTHOR

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.

BUGS

copytape treats two successive file marks as logical end-of-tape.

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.