umount detaches the file system(s) mentioned from the file hierarchy. A file system is specified by giving the directory where it has been mounted.
print version and exits.
invokes verbose mode.
unmounts without writing in /etc/mtab.
tries to remount read-only if unmounting fails.
unmounts all of the file systems described in /etc/mtab except for the proc filesystem.
indicates that the actions should only be taken on file systems of the specified type. More than one type may be specified in a comma separated list. The list of file system types can be prefixed with no to specify the file system types on which no action should be taken.
forces unmount (in case of an unreachable NFS system).