Manual: umount

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       is obsolete, mainly because it will fail in case this device was mounted on more than one directory.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. 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=
	   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 .

AVAILABILITY
       The umount command is part of the util-linux package which can be downloaded from Linux Kernel Archive
       .

util-linux 2.41.3					 2025-12-15						   UMOUNT(8)