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.Dd June 19, 2020 29.Dt UMOUNT 8 30.Os 31.Sh NAME 32.Nm umount 33.Nd unmount file systems 34.Sh SYNOPSIS 35.Nm 36.Op Fl fNnv 37.Ar special ... | node ... | fsid ... 38.Nm 39.Fl a | A 40.Op Fl F Ar fstab 41.Op Fl fnv 42.Op Fl h Ar host 43.Op Fl t Ar type 44.Sh DESCRIPTION 45The 46.Nm 47utility calls the 48.Xr unmount 2 49system call to remove a file system from the file system tree. 50The file system can be specified by its 51.Ar special 52device or remote node 53.Pq Ar rhost Ns Cm \& : Ns Ar path , 54the path to the mount point 55.Ar node 56or by the file system ID 57.Ar fsid 58as reported by 59.Dq mount -v 60when run by root. 61.Pp 62The options are as follows: 63.Bl -tag -width "-F fstab" 64.It Fl a 65All the file systems described in 66.Xr fstab 5 67are unmounted. 68.It Fl A 69All the currently mounted file systems are unmounted, 70except for those mounted at 71.Pa / 72or 73.Pa /dev . 74.It Fl F Ar fstab 75Specify the 76.Pa fstab 77file to use. 78.It Fl f 79The file system is forcibly unmounted. 80Active special devices continue to work, 81but all other files return errors if further accesses are attempted. 82The root file system cannot be forcibly unmounted. 83For NFS, a forced dismount can take up to 1 minute or more to 84complete against an unresponsive server and may throw away 85data not yet written to the server for this case. 86If a process, such as 87.Nm 88without the 89.Fl f 90flag is hung on an 91.Tn NFS 92mount point, use the 93.Fl N 94flag instead. 95Also, doing a forced dismount of an NFSv3 mount when 96.Xr rpc.lockd 8 97is running is unsafe and can result in a crash. 98.It Fl h Ar host 99Only file systems mounted from the specified host will be 100unmounted. 101This option implies the 102.Fl A 103option and, unless otherwise specified with the 104.Fl t 105option, will only unmount 106.Tn NFS 107file systems. 108.It Fl N 109Do a forced dismount of an 110.Tn NFS 111mount point without checking the mount path. 112This option can only be used with the path to the mount point 113.Ar node 114and the path must be specified exactly as it was at mount time. 115This option is useful when a process is hung waiting for an unresponsive 116.Tn NFS 117server while holding a vnode lock on the mounted-on vnode, such that 118.Nm 119with the 120.Fl f 121flag can't complete. 122Using this option can result in a loss of file updates that have not been 123flushed to the 124.Tn NFS 125server. 126.It Fl n 127Unless the 128.Fl f 129is used, the 130.Nm 131will not unmount an active file system. 132It will, however, perform a flush. 133This flag disables this behaviour, preventing the flush 134if there are any files open. 135.It Fl t Ar type 136Is used to indicate the actions should only be taken on 137file systems of the specified type. 138More than one type may be specified in a comma separated list. 139The list of file system types can be prefixed with 140.Dq no 141to specify the file system types for which action should 142.Em not 143be taken. 144For example, the 145.Nm 146command: 147.Bd -literal -offset indent 148umount -a -t nfs,nullfs 149.Ed 150.Pp 151unmounts all file systems of the type 152.Tn NFS 153and 154.Tn NULLFS 155that are listed in the 156.Xr fstab 5 157file. 158.It Fl v 159Verbose, additional information is printed out as each file system 160is unmounted. 161.El 162.Sh ENVIRONMENT 163.Bl -tag -width ".Ev PATH_FSTAB" 164.It Ev PATH_FSTAB 165If the environment variable 166.Ev PATH_FSTAB 167is set, all operations are performed against the specified file. 168.Ev PATH_FSTAB 169will not be honored if the process environment or memory address space is 170considered 171.Dq tainted . 172(See 173.Xr issetugid 2 174for more information.) 175.El 176.Sh FILES 177.Bl -tag -width /etc/fstab -compact 178.It Pa /etc/fstab 179file system table 180.El 181.Sh SEE ALSO 182.Xr unmount 2 , 183.Xr fstab 5 , 184.Xr autounmountd 8 , 185.Xr mount 8 186.Sh HISTORY 187A 188.Nm 189utility appeared in 190.At v1 . 191