tar .vs. cpio

[dan at idis.UUCP]

I believe that the history of the "tar" program reported during the
"tar .vs. cpio" debate in net.unix is a bit confused.  The "tar" program
is from unix V7 and was intended to provide a convenient and machine
independent way of sending collections of files (e.g. a software
distribution) to other machines.  The most immediate ancestor of "tar"
is probably "ar".  Before version 7 (i.e. version 6), we used ad hoc
combinations of "tp", "ar", and "dd".  I suspect that "tp" was originally
designed to work with dectapes (small replaceable blocks) and extended
to handle 9 track mag tapes (potentially large but nonreplaceable blocks)
as an afterthought.

I doubt that "tar" was originally intended to be used for system backup.
This is why most versions of "tar" cannot handle special files or
multiple volumes.

The "cpio" program comes from PWB unix (which was developed at about the
same time as V7 but by a different group of people).  I imagine that
"cpio" was developed for some of the same reasons as "tar" ("tp", "ar",
and "dd" being inadequate).

				Dan Strick
				University of Pittsburgh
				[decvax|mcnc]!idis!dan