//eettcc//uummoouunntt _s_p_e_c_i_a_lumount unmounts a file system special that was previously mounted with the mount command.
The script /bin/umount calls /etc/umount, and provides convenient abbreviations for commonly used devices. For example, typing
umount f0
executes the command
/etc/umount /dev/fha0
The system administrator should edit this script to reflect the devices used on your specific system.