1.\" Copyright (c) 1980, 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)umount.8 8.2 (Berkeley) 5/8/95 29.\" $FreeBSD$ 30.\" 31.Dd September 10, 2016 32.Dt UMOUNT 8 33.Os 34.Sh NAME 35.Nm umount 36.Nd unmount file systems 37.Sh SYNOPSIS 38.Nm 39.Op Fl fnv 40.Ar special ... | node ... | fsid ... 41.Nm 42.Fl a | A 43.Op Fl F Ar fstab 44.Op Fl fnv 45.Op Fl h Ar host 46.Op Fl t Ar type 47.Sh DESCRIPTION 48The 49.Nm 50utility calls the 51.Xr unmount 2 52system call to remove a file system from the file system tree. 53The file system can be specified by its 54.Ar special 55device or remote node (rhost:path), the path to the mount point 56.Ar node 57or by the file system ID 58.Ar fsid 59as reported by 60.Dq mount -v 61when run by root. 62.Pp 63The options are as follows: 64.Bl -tag -width indent 65.It Fl a 66All the file systems described in 67.Xr fstab 5 68are unmounted. 69.It Fl A 70All the currently mounted file systems except 71the root are unmounted. 72.It Fl F Ar fstab 73Specify the 74.Pa fstab 75file to use. 76.It Fl f 77The file system is forcibly unmounted. 78Active special devices continue to work, 79but all other files return errors if further accesses are attempted. 80The root file system cannot be forcibly unmounted. 81For NFS, a forced dismount can take up to 1 minute or more to 82complete against an unresponsive server and may throw away 83data not yet written to the server for this case. 84Also, doing a forced dismount of an NFSv3 mount when 85.Xr rpc.lockd 8 86is running is unsafe and can result in a crash. 87.It Fl h Ar host 88Only file systems mounted from the specified host will be 89unmounted. 90This option implies the 91.Fl A 92option and, unless otherwise specified with the 93.Fl t 94option, will only unmount 95.Tn NFS 96file systems. 97.It Fl n 98Unless the 99.Fl f 100is used, the 101.Nm 102will not unmount an active file system. 103It will, however, perform a flush. 104This flag disables this behaviour, preventing the flush 105if there are any files open. 106.It Fl t Ar type 107Is used to indicate the actions should only be taken on 108file systems of the specified type. 109More than one type may be specified in a comma separated list. 110The list of file system types can be prefixed with 111.Dq no 112to specify the file system types for which action should 113.Em not 114be taken. 115For example, the 116.Nm 117command: 118.Bd -literal -offset indent 119umount -a -t nfs,nullfs 120.Ed 121.Pp 122unmounts all file systems of the type 123.Tn NFS 124and 125.Tn NULLFS 126that are listed in the 127.Xr fstab 5 128file. 129.It Fl v 130Verbose, additional information is printed out as each file system 131is unmounted. 132.El 133.Sh ENVIRONMENT 134.Bl -tag -width ".Ev PATH_FSTAB" 135.It Ev PATH_FSTAB 136If the environment variable 137.Ev PATH_FSTAB 138is set, all operations are performed against the specified file. 139.Ev PATH_FSTAB 140will not be honored if the process environment or memory address space is 141considered 142.Dq tainted . 143(See 144.Xr issetugid 2 145for more information.) 146.El 147.Sh FILES 148.Bl -tag -width /etc/fstab -compact 149.It Pa /etc/fstab 150file system table 151.El 152.Sh SEE ALSO 153.Xr unmount 2 , 154.Xr fstab 5 , 155.Xr autounmountd 8 , 156.Xr mount 8 157.Sh HISTORY 158A 159.Nm 160utility appeared in 161.At v1 . 162