UMOUNT(8)		     System Administration		     UMOUNT(8)

NAME
       umount - unmount filesystems

SYNOPSIS
       umount -a [-dflnrv] [-t fstype] [-O option...]

       umount [-dflnrv] {directory|device}

       umount -h|-V

DESCRIPTION
       The umount command detaches the mentioned filesystem(s) from the file
       hierarchy. A filesystem is specified by giving the directory where it
       has been mounted. Giving the special device on which the filesystem
       lives may also work, but is obsolete, mainly because it will fail in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 filesystem 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, but it may introduce other issues. See --lazy description
       below.

OPTIONS
       -a, --all
	   All of the filesystems described in /proc/self/mountinfo (or in
	   deprecated /etc/mtab) are unmounted, except the proc, devfs,
	   devpts, sysfs, rpc_pipefs and nfsd filesystems. This list of the
	   filesystems may be replaced by --types umount option.

       -A, --all-targets
	   Unmount all mountpoints in the current mount 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. The paths canonicalization is based on
	   stat(2) and readlink(2) system calls. These system calls may hang
	   in some cases (for example on NFS if server is not available). The
	   option has to be used with canonical path to the mount point.

	   This option is silently ignored by umount for non-root users.

	   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. This option is unnecessary for devices initialized by
	   mount(8), in this case "autoclear" functionality is enabled by
	   default.

       --fake
	   Causes everything to be done except for the actual system call or
	   umount helper execution; this 'fakes' unmounting the filesystem. It
	   can be used to remove entries from the deprecated /etc/mtab that
	   were unmounted earlier with the -n option.

       -f, --force
	   Force an unmount (in case of an unreachable NFS system).

	   Note that this option does not guarantee that umount command does
	   not hang. It’s strongly recommended to use absolute paths without
	   symlinks to avoid unwanted readlink(2) and stat(2) system calls on
	   unreachable NFS in umount.

       -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.

	   A system reboot would be expected in near future if you’re going to
	   use this option for network filesystem or local filesystem with
	   submounts. The recommended use-case for umount -l is to prevent
	   hangs on shutdown due to an unreachable network share where a
	   normal umount will hang due to a downed server or a network
	   partition. Remounts of the share will not be possible.

       -N, --namespace ns
	   Perform umount in the mount namespace specified by ns. ns is either
	   PID of process running in that namespace or special file
	   representing that namespace.

	   umount switches to the namespace when it reads /etc/fstab, writes
	   /etc/mtab (or writes to /run/mount) and calls umount(2) system
	   call, otherwise it runs in the original namespace. It means that
	   the target mount namespace does not have to contain any libraries
	   or other requirements necessary to execute umount(2) command.

	   See mount_namespaces(7) for more information.

       -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.

       -q, --quiet
	   Suppress "not mounted" error messages.

       -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. Since version 2.37 it umounts also all over-mounted
	   filesystems (more filesystems on the same mountpoint).

       -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. Note that umount reads information about mounted
	   filesystems from kernel (/proc/mounts) and filesystem names may be
	   different than filesystem names used in the /etc/fstab (e.g.,
	   "nfs4" vs. "nfs").

       -v, --verbose
	   Verbose mode.

       -h, --help
	   Display help text and exit.

       -V, --version
	   Display version and exit.

NON-SUPERUSER UMOUNTS
       Normally, only the superuser can umount filesystems. However, when
       fstab contains the user option on a line, anybody can umount the
       corresponding filesystem. For more details see mount(8) man page.

       Since version 2.34 the umount command can be used to perform umount
       operation also for fuse filesystems if kernel mount table contains
       user’s ID. In this case fstab user= mount option is not required.

       Since version 2.35 umount command does not exit when user permissions
       are inadequate by internal libmount security rules. It drops suid
       permissions and continue as regular non-root user. This can be used to
       support use-cases where root permissions are not necessary (e.g., fuse
       filesystems, user namespaces, etc).

LOOP DEVICE
       The umount command will automatically detach loop device previously
       initialized by mount(8) command independently of /etc/mtab.

       In this case the device is initialized with "autoclear" flag (see
       losetup(8) output for more details), otherwise it’s necessary to use
       the option --detach-loop or call losetup -d device. The autoclear
       feature is supported since Linux 2.6.25.

       Note that since Linux v3.7 kernel uses "lazy device destruction". The
       system just marks the loop device by autoclear flag and destroys it
       later. If you need to wait for a complete removal of the loop device,
       call udevadm settle after umount.

EXIT STATUS
       umount has the following exit status values (the bits can be ORed):

       0
	   success

       1
	   incorrect invocation or permissions

       2
	   system error (out of memory, cannot fork, no more loop devices)

       4
	   internal mount bug

       8
	   user interrupt

       16
	   problems writing or locking /etc/mtab

       32
	   mount failure

       64
	   some umount succeeded

	   The command umount -a returns 0 (all succeeded), 32 (all failed),
	   or 64 (some failed, some succeeded).

       126
	   failed to execute external /sbin/umount.<type> mount helper (since
	   util-linux v2.41)

EXTERNAL HELPERS
       The syntax of external unmount helpers is:

	  umount.suffix {directory|device} [-flnrv] [-N namespace] [-t
	  type.subtype]

       where suffix is the filesystem type (or the value from a uhelper= or
       helper= marker in the mtab file). The -t option can be used for
       filesystems that have subtype support. For example:

	  umount.fuse -t fuse.sshfs

       A uhelper=something marker (unprivileged helper) can appear in the
       /etc/mtab file when ordinary users need to be able to unmount a
       mountpoint that is not defined in /etc/fstab (for example for a device
       that was mounted by udisks(1)).

       A helper=type marker in the mtab file will redirect all unmount
       requests to the /sbin/umount.type helper independently of UID.

       Note that /etc/mtab is currently deprecated and helper= and other
       userspace mount options are maintained by libmount.

       The exit status value of the helper is returned as the exit status of
       umount(8). The value 126 is used if the mount helper program is found,
       but the execl() failed.

ENVIRONMENT
       LIBMOUNT_FSTAB=<path>
	   overrides the default location of the fstab file (ignored for suid)

       LIBMOUNT_DEBUG=all
	   enables libmount debug output

FILES
       /etc/mtab
	   table of mounted filesystems (deprecated and usually replaced by
	   symlink to /proc/mounts)

       /etc/fstab
	   table of known filesystems

       /proc/self/mountinfo
	   table of mounted filesystems generated by kernel.

HISTORY
       A umount command appeared in Version 6 AT&T UNIX.

SEE ALSO
       umount(2), losetup(8), mount_namespaces(7), mount(8)

REPORTING BUGS
       For bug reports, use the issue tracker
       <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY
       The umount command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>.

util-linux 2.41.2		  2025-09-22			     UMOUNT(8)