Section: System Administration (8)
Updated: July 2014Index
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umount - unmount file systems
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also work, but is obsolete, mainly because it will fail in case this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
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
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
- -c, --no-canonicalize
Do not canonicalize paths. For more details about this option see the
man page. Note that umount does not pass this option to the
- -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
that were unmounted earlier with the
- -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
- -O, --test-opts option...
Unmount only the filesystems that have the specified option set in
More than one option may be specified in a comma-separated list.
Each option can be prefixed with
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)
- -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
More than one type may be specified in a comma-separated list. The list
of filesystem types can be prefixed with
to indicate that no action should be taken for all of the mentioned types.
- -v, --verbose
- -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 losetup -d
The syntax of external unmount helpers is:
where suffix is the filesystem type or a value from a "uhelper=" or
"helper=" mtab option. The -t option can be used for filesystems
with subtypes support (for example /sbin/mount.fuse -t fuse.sshfs).
The uhelper= (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 /etc/fstab (e.g. devices mounted by udisk).
The helper= mount option redirects all unmount requests to the
/sbin/umount.type 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
Linux Kernel Archive
- LOOP DEVICE
- EXTERNAL HELPERS
- SEE ALSO