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 July 25, 2017 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 fNnv 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. 84If a process, such as 85.Nm 86without the 87.Fl f 88flag is hung on an 89.Tn NFS 90mount point, use the 91.Fl N 92flag instead. 93Also, doing a forced dismount of an NFSv3 mount when 94.Xr rpc.lockd 8 95is running is unsafe and can result in a crash. 96.It Fl h Ar host 97Only file systems mounted from the specified host will be 98unmounted. 99This option implies the 100.Fl A 101option and, unless otherwise specified with the 102.Fl t 103option, will only unmount 104.Tn NFS 105file systems. 106.It Fl N 107Do a forced dismount of an 108.Tn NFS 109mount point without checking the mount path. 110This option can only be used with the path to the mount point 111.Ar node 112and the path must be specified exactly as it was at mount time. 113This option is useful when a process is hung waiting for an unresponsive 114.Tn NFS 115server while holding a vnode lock on the mounted-on vnode, such that 116.Nm 117with the 118.Fl f 119flag can't complete. 120Using this option can result in a loss of file updates that have not been 121flushed to the 122.Tn NFS 123server. 124.It Fl n 125Unless the 126.Fl f 127is used, the 128.Nm 129will not unmount an active file system. 130It will, however, perform a flush. 131This flag disables this behaviour, preventing the flush 132if there are any files open. 133.It Fl t Ar type 134Is used to indicate the actions should only be taken on 135file systems of the specified type. 136More than one type may be specified in a comma separated list. 137The list of file system types can be prefixed with 138.Dq no 139to specify the file system types for which action should 140.Em not 141be taken. 142For example, the 143.Nm 144command: 145.Bd -literal -offset indent 146umount -a -t nfs,nullfs 147.Ed 148.Pp 149unmounts all file systems of the type 150.Tn NFS 151and 152.Tn NULLFS 153that are listed in the 154.Xr fstab 5 155file. 156.It Fl v 157Verbose, additional information is printed out as each file system 158is unmounted. 159.El 160.Sh ENVIRONMENT 161.Bl -tag -width ".Ev PATH_FSTAB" 162.It Ev PATH_FSTAB 163If the environment variable 164.Ev PATH_FSTAB 165is set, all operations are performed against the specified file. 166.Ev PATH_FSTAB 167will not be honored if the process environment or memory address space is 168considered 169.Dq tainted . 170(See 171.Xr issetugid 2 172for more information.) 173.El 174.Sh FILES 175.Bl -tag -width /etc/fstab -compact 176.It Pa /etc/fstab 177file system table 178.El 179.Sh SEE ALSO 180.Xr unmount 2 , 181.Xr fstab 5 , 182.Xr autounmountd 8 , 183.Xr mount 8 184.Sh HISTORY 185A 186.Nm 187utility appeared in 188.At v1 . 189