UMOUNT(8) manual page
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umount - unmount file systems
umount
-a [-dflnrv] [-t fstype] [-O option...]
umount [-dflnrv] {directory|device}...
umount
-
h|-V
The umount 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system lives may also work, but is obsolete, mainly because it will fail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 device.
- --fake
- 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 option.
- -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 mentioned types.
- -v, --verbose
- Verbose mode.
- -V, --version
- Display
version information and exit.
- -h, --help
- Display help text and exit.
The
umount command will free the loop device associated with a mount when it
finds the option loop=... in /etc/mtab, or when the -d option was given. Any
still associated loop devices can be freed by using losetup -d; see losetup(8)
.
The syntax of external unmount helpers is:
/sbin/umount.suffix
{directory|device} [-flnrv] [-t type.subtype]
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.
- /etc/mtab
- table of mounted filesystems
- /etc/fstab
- checked when option -O is given
- LIBMOUNT_FSTAB=<path>
- overrides
the default location of the fstab file
- LIBMOUNT_MTAB=<path>
- overrides the
default location of the mtab file
- LIBMOUNT_DEBUG=0xffff
- enables debug output
umount(2)
, mount(8)
, losetup(8)
A umount 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
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