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       lives may also work, but is obsolete, mainly because it will fail in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