This command enables you to remove a remote file system that is currently mounted. The umount command supports the -V option to allow for testing. You might also use the -a option to umount several file systems at one time. If mount_points are included with the -a option, those file systems are unmounted. If no mount points are included, an attempt is made to unmount all file systems listed in /etc/mnttab, except for the "required" file systems, such as /, /usr, /var, /proc, /dev/fd, and /tmp.
Because the file system is already mounted and should have an entry in /etc/mnttab, you do not need to include a flag for the file-system type.
The command cannot succeed if the file system is in use. For instance, if a user has used cd to get access to a file system, the file system is busy until the working directory is changed. The umount command can hang temporarily if the NFS server is unreachable.
This example unmounts a file system mounted on /usr/man:
# umount /usr/man |
This example displays the results of running umount -a -V:
# umount -a -V umount /home/kathys umount /opt umount /home umount /net |
Notice that this command does not actually unmount the file systems.