Tape-related commands

[Kenneth Porter]

I backup my systems using first "bar Z" to a disk file, then "cp" to
/dev/rst8, and verify the result with "diff -h $barfile $TAPE".  I've
always seen examples of tape copying (to or from disk) using the "dd"
command.  Is "cp" the wrong thing to use?  Can someone offer a brief
tutorial on the subtleties of using ordinary file commands with tape (and
other) devices?

Ken (shiva at well.sf.ca.us)