umount — unmount file systems
umount [−hV]
umount −a [−dflnrv] [ −t vfstype ] [ −O options ]
umount [−dflnrv] dir | device [ ... ]
The umount command detaches the file system(s) mentioned from the file hierarchy. A file system is specified by giving the directory where it has been mounted. Giving the special device on which the file system lives may also work, but is obsolete, mainly because it will fail in case this device was mounted on more than one directory.
Note that a file system cannot be unmounted when it is `busy' - for example, when there are open files on it, or when some process has its working directory there, or when a swap file on it is in use. The offending process could even be umount itself - it opens libc, and libc in its turn may open for example locale files. A lazy unmount avoids this problem.
Options for the umount command:
−VPrint version and exit.
−hPrint help message and exit.
−vVerbose mode.
−nUnmount without writing in /etc/mtab.
−rIn case unmounting fails, try to remount read-only.
−dIn case the unmounted device was a loop device, also free this loop device.
−iDon't call the /sbin/umount.<filesystem> helper even if it exists. By default /sbin/umount.<filesystem> helper is called if one exists.
−aAll of the file systems described in /etc/mtab are unmounted. (With
umount
version 2.7 and later: the proc filesystem is not unmounted.)
−t
vfstypeIndicate 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.
−O
optionsIndicate that the actions should only be taken on
file systems with the specified options in /etc/fstab. More than one option type
may be specified in a comma separated list. Each option
can be prefixed with no to
specify options for which no action should be
taken.
−fForce unmount (in case of an unreachable NFS system). (Requires kernel 2.1.116 or later.)
−lLazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. (Requires kernel 2.4.11 or later.)
The umount
command will free the loop device (if any) associated with
the mount, in case it finds the option `loop=...' in
/etc/mtab, or when the −d
option was given. Any pending loop devices can be freed using
`losetup -d', see losetup(8).