umount - unmount file systems
] [-t fstype
command detaches the mentioned file system(s) 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also work, but is obsolete, mainly because it will fail in case this device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.
- -a, --all
- All of the filesystems described in /etc/mtab are unmounted, except
the proc filesystem.
- -A, --all-targets
- Unmount all mountpoints in the current namespace for the specified
filesystem. The filesystem can be specified by one of the mountpoints or
the device name (or UUID, etc.). When this option is used together with
--recursive, then all nested mounts within the filesystem are
recursively unmounted. This option is only supported on systems where
/etc/mtab is a symlink to /proc/mounts.
- -c, --no-canonicalize
- Do not canonicalize paths. For more details about this option see the
mount(8) man page. Note that umount does not pass this
option to the /sbin/umount.type helpers.
- -d, --detach-loop
- When the unmounted device was a loop device, also free this loop
- Causes everything to be done except for the actual system call; this
'fakes' unmounting the filesystem. It can be used to remove entries from
/etc/mtab that were unmounted earlier with the -n
- -f, --force
- Force an unmount (in case of an unreachable NFS system). (Requires kernel
2.1.116 or later.)
- -i, --internal-only
- Do not call the /sbin/umount.filesystem helper even if it
exists. By default such a helper program is called if it exists.
- -l, --lazy
- Lazy unmount. Detach the filesystem from the file hierarchy now, and clean
up all references to this filesystem as soon as it is not busy anymore.
(Requires kernel 2.4.11 or later.)
- -n, --no-mtab
- Unmount without writing in /etc/mtab.
- -O, --test-opts option...
- Unmount only the filesystems that have the specified option set in
/etc/fstab. More than one option may be specified in a
comma-separated list. Each option can be prefixed with no to
indicate that no action should be taken for this option.
- -R, --recursive
- Recursively unmount each specified directory. Recursion for each directory
will stop if any unmount operation in the chain fails for any reason. The
relationship between mountpoints is determined by /proc/self/mountinfo
entries. The filesystem must be specified by mountpoint path; a recursive
unmount by device name (or UUID) is unsupported.
- -r, --read-only
- When an unmount fails, try to remount the filesystem read-only.
- -t, --types type...
- Indicate that the actions should only be taken on filesystems of the
specified type. More than one type may be specified in a
comma-separated list. The list of filesystem types can be prefixed with
no to indicate that no action should be taken for all of the
- -v, --verbose
- Verbose mode.
- -V, --version
- Display version information and exit.
- -h, --help
- Display help text and exit.
command will free the loop device associated with a mount when
it finds the option loop=...
, or when the -d
option was given. Any still associated loop devices can be freed by using
; see losetup(8)
The syntax of external unmount helpers is:
] [-t type
is the filesystem type or a value from a
"uhelper=" or "helper=" mtab option. The -t
can be used for filesystems with subtypes support (for example
/sbin/mount.fuse -t fuse.sshfs
(unprivileged unmount helper) mount option can be used when
non-root users need to be able to unmount a mountpoint which is not defined in
(e.g. devices mounted by udisk).
mount option redirects all unmount requests to the
helper independently of UID.
- table of mounted filesystems
- checked when option -O is given
- overrides the default location of the fstab file
- overrides the default location of the mtab file
- enables debug output
command appeared in Version 6 AT&T UNIX.
The umount command is part of the util-linux package and is available from