UMOUNT(8)               FreeBSD System Manager's Manual              UMOUNT(8)

NAME
     umount - unmount file systems

SYNOPSIS
     umount [-fNnv] special ... | node ... | fsid ...
     umount -a | -A [-F fstab] [-fnv] [-h host] [-t type]

DESCRIPTION
     The umount utility calls the unmount(2) system call to remove a file
     system from the file system tree.  The file system can be specified by
     its special device or remote node (rhost:path), the path to the mount
     point node or by the file system ID fsid as reported by "mount -v" when
     run by root.

     The options are as follows:

     -a        All the file systems described in fstab(5) are unmounted.

     -A        All the currently mounted file systems are unmounted, except
               for those mounted at / or /dev.

     -F fstab  Specify the fstab file to use.

     -f        The file system is forcibly unmounted.  Active special devices
               continue to work, but all other files return errors if further
               accesses are attempted.  The root file system cannot be
               forcibly unmounted.  For NFS, a forced dismount can take up to
               1 minute or more to complete against an unresponsive server and
               may throw away data not yet written to the server for this
               case.  If a process, such as umount without the -f flag is hung
               on an NFS mount point, use the -N flag instead.  Also, doing a
               forced dismount of an NFSv3 mount when rpc.lockd(8) is running
               is unsafe and can result in a crash.

     -h host   Only file systems mounted from the specified host will be
               unmounted.  This option implies the -A option and, unless
               otherwise specified with the -t option, will only unmount NFS
               file systems.

     -N        Do a forced dismount of an NFS mount point without checking the
               mount path.  This option can only be used with the path to the
               mount point node and the path must be specified exactly as it
               was at mount time.  This option is useful when a process is
               hung waiting for an unresponsive NFS server while holding a
               vnode lock on the mounted-on vnode, such that umount with the
               -f flag can't complete.  Using this option can result in a loss
               of file updates that have not been flushed to the NFS server.

     -n        Unless the -f is used, the umount will not unmount an active
               file system.  It will, however, perform a flush.  This flag
               disables this behaviour, preventing the flush if there are any
               files open.

     -t type   Is used to indicate the actions should only be taken on file
               systems of the specified type.  More than one type may be
               specified in a comma separated list.  The list of file system
               types can be prefixed with "no" to specify the file system
               types for which action should not be taken.  For example, the
               umount command:

                     umount -a -t nfs,nullfs

               unmounts all file systems of the type NFS and NULLFS that are
               listed in the fstab(5) file.

     -v        Verbose, additional information is printed out as each file
               system is unmounted.

ENVIRONMENT
     PATH_FSTAB      If the environment variable PATH_FSTAB is set, all
                     operations are performed against the specified file.
                     PATH_FSTAB will not be honored if the process environment
                     or memory address space is considered "tainted".  (See
                     issetugid(2) for more information.)

FILES
     /etc/fstab  file system table

SEE ALSO
     unmount(2), fstab(5), autounmountd(8), mount(8)

HISTORY
     A umount utility appeared in Version 1 AT&T UNIX.

FreeBSD 13.1-RELEASE-p6          June 19, 2020         FreeBSD 13.1-RELEASE-p6