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UMOUNT(8)		    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 de-
		 vices 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 un-
		 mounted.  This	option implies the -A option and, unless  oth-
		 erwise	 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  ex-
		 actly	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	opera-
		   tions 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	13.2			 June 19, 2020			     UMOUNT(8)

NAME | SYNOPSIS | DESCRIPTION | ENVIRONMENT | FILES | SEE ALSO | HISTORY

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