Hi,
usually people wants to umount/mount a filesystem in order to change option (eg. largefiles) or take a fsck on it or enlarge/decrease the size. If you have OnlineJFS you can simply accomplish last operation, in all other cases you need to umount/mount again the filesystem. I never heard about re-mount a filesystem on HP-UX.
Maybe a
mount /opt
should be sufficient, but pretty sure will give the message 'already mounted' for /opt.
Otherwise please clear better your needs.
Best regards,
Fabio
WISH? IMPROVEMENT!