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.\" 30.Dd June 19, 2020 31.Dt UMOUNT 8 32.Os 33.Sh NAME 34.Nm umount 35.Nd unmount file systems 36.Sh SYNOPSIS 37.Nm 38.Op Fl fNnv 39.Ar special ... | node ... | fsid ... 40.Nm 41.Fl a | A 42.Op Fl F Ar fstab 43.Op Fl fnv 44.Op Fl h Ar host 45.Op Fl t Ar type 46.Sh DESCRIPTION 47The 48.Nm 49utility calls the 50.Xr unmount 2 51system call to remove a file system from the file system tree. 52The file system can be specified by its 53.Ar special 54device or remote node 55.Pq Ar rhost Ns Cm \& : Ns Ar path , 56the path to the mount point 57.Ar node 58or by the file system ID 59.Ar fsid 60as reported by 61.Dq mount -v 62when run by root. 63.Pp 64The options are as follows: 65.Bl -tag -width "-F fstab" 66.It Fl a 67All the file systems described in 68.Xr fstab 5 69are unmounted. 70.It Fl A 71All the currently mounted file systems are unmounted, 72except for those mounted at 73.Pa / 74or 75.Pa /dev . 76.It Fl F Ar fstab 77Specify the 78.Pa fstab 79file to use. 80.It Fl f 81The file system is forcibly unmounted. 82Active special devices continue to work, 83but all other files return errors if further accesses are attempted. 84The root file system cannot be forcibly unmounted. 85For NFS, a forced dismount can take up to 1 minute or more to 86complete against an unresponsive server and may throw away 87data not yet written to the server for this case. 88If a process, such as 89.Nm 90without the 91.Fl f 92flag is hung on an 93.Tn NFS 94mount point, use the 95.Fl N 96flag instead. 97Also, doing a forced dismount of an NFSv3 mount when 98.Xr rpc.lockd 8 99is running is unsafe and can result in a crash. 100.It Fl h Ar host 101Only file systems mounted from the specified host will be 102unmounted. 103This option implies the 104.Fl A 105option and, unless otherwise specified with the 106.Fl t 107option, will only unmount 108.Tn NFS 109file systems. 110.It Fl N 111Do a forced dismount of an 112.Tn NFS 113mount point without checking the mount path. 114This option can only be used with the path to the mount point 115.Ar node 116and the path must be specified exactly as it was at mount time. 117This option is useful when a process is hung waiting for an unresponsive 118.Tn NFS 119server while holding a vnode lock on the mounted-on vnode, such that 120.Nm 121with the 122.Fl f 123flag can't complete. 124Using this option can result in a loss of file updates that have not been 125flushed to the 126.Tn NFS 127server. 128.It Fl n 129Unless the 130.Fl f 131is used, the 132.Nm 133will not unmount an active file system. 134It will, however, perform a flush. 135This flag disables this behaviour, preventing the flush 136if there are any files open. 137.It Fl t Ar type 138Is used to indicate the actions should only be taken on 139file systems of the specified type. 140More than one type may be specified in a comma separated list. 141The list of file system types can be prefixed with 142.Dq no 143to specify the file system types for which action should 144.Em not 145be taken. 146For example, the 147.Nm 148command: 149.Bd -literal -offset indent 150umount -a -t nfs,nullfs 151.Ed 152.Pp 153unmounts all file systems of the type 154.Tn NFS 155and 156.Tn NULLFS 157that are listed in the 158.Xr fstab 5 159file. 160.It Fl v 161Verbose, additional information is printed out as each file system 162is unmounted. 163.El 164.Sh ENVIRONMENT 165.Bl -tag -width ".Ev PATH_FSTAB" 166.It Ev PATH_FSTAB 167If the environment variable 168.Ev PATH_FSTAB 169is set, all operations are performed against the specified file. 170.Ev PATH_FSTAB 171will not be honored if the process environment or memory address space is 172considered 173.Dq tainted . 174(See 175.Xr issetugid 2 176for more information.) 177.El 178.Sh FILES 179.Bl -tag -width /etc/fstab -compact 180.It Pa /etc/fstab 181file system table 182.El 183.Sh SEE ALSO 184.Xr unmount 2 , 185.Xr fstab 5 , 186.Xr autounmountd 8 , 187.Xr mount 8 188.Sh HISTORY 189A 190.Nm 191utility appeared in 192.At v1 . 193