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

     umount -- unmount file systems

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

     The umount	utility	calls the unmount(2) system call to remove a file sys-
     tem 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

     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 un-
	       mounted.	 This option implies the -A option and,	unless other-
	       wise specified with the -t option, will only unmount NFS	file

     -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 vn-
	       ode 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 spec-
	       ified 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 com-

		     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.

     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

     /etc/fstab	 file system table

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

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

FreeBSD	13.0			 June 19, 2020			  FreeBSD 13.0


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