That's odd. Try `man mt` or `/bin/mt status`. I'm not a Red Hat user, so I have to rely on google. I found a couple of discussions with people asking where mt was on rhel5. Outside chance it's not installed (check `rpm -ql mt`)? Try installing it (`rpm -ivh mt-st-0.9b-2.2.2.x86_64` or alternative from list below).
According to Red Hat Network:
mt-st-0.9b-2.2.2.x86_64 Red Hat Enterprise Linux (v. 5 for 64-bit x86_64)
mt-st-0.9b-2.2.2.i386 Red Hat Enterprise Linux (v. 5 for 32-bit x86)
mt-st-0.9b-2.2.2.ia64 Red Hat Enterprise Linux (v. 5 for 64-bit Itanium)
Those suggestions came from the following:
http://linux.derkeiler.com/Mailing-L.../msg00180.html
http://forums11.itrc.hp.com/service/...readId=1282808