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 January 16, 2024 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 dfNnv 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 d 75If the filesystem is mounted on an 76.Xr md 4 77device (a memory disk), detach it after 78.Xr unmount 2 . 79.It Fl F Ar fstab 80Specify the 81.Pa fstab 82file to use. 83.It Fl f 84The file system is forcibly unmounted. 85Active special devices continue to work, 86but all other files return errors if further accesses are attempted. 87The root file system cannot be forcibly unmounted. 88For NFS, a forced dismount can take up to 1 minute or more to 89complete against an unresponsive server and may throw away 90data not yet written to the server for this case. 91If a process, such as 92.Nm 93without the 94.Fl f 95flag is hung on an 96.Tn NFS 97mount point, use the 98.Fl N 99flag instead. 100Also, doing a forced dismount of an NFSv3 mount when 101.Xr rpc.lockd 8 102is running is unsafe and can result in a crash. 103.It Fl h Ar host 104Only file systems mounted from the specified host will be 105unmounted. 106This option implies the 107.Fl A 108option and, unless otherwise specified with the 109.Fl t 110option, will only unmount 111.Tn NFS 112file systems. 113.It Fl N 114Do a forced dismount of an 115.Tn NFS 116mount point without checking the mount path. 117This option can only be used with the path to the mount point 118.Ar node 119and the path must be specified exactly as it was at mount time. 120This option is useful when a process is hung waiting for an unresponsive 121.Tn NFS 122server while holding a vnode lock on the mounted-on vnode, such that 123.Nm 124with the 125.Fl f 126flag can't complete. 127Using this option can result in a loss of file updates that have not been 128flushed to the 129.Tn NFS 130server. 131.It Fl n 132Unless the 133.Fl f 134is used, the 135.Nm 136will not unmount an active file system. 137It will, however, perform a flush. 138This flag disables this behaviour, preventing the flush 139if there are any files open. 140.It Fl t Ar type 141Is used to indicate the actions should only be taken on 142file systems of the specified type. 143More than one type may be specified in a comma separated list. 144The list of file system types can be prefixed with 145.Dq no 146to specify the file system types for which action should 147.Em not 148be taken. 149For example, the 150.Nm 151command: 152.Bd -literal -offset indent 153umount -a -t nfs,nullfs 154.Ed 155.Pp 156unmounts all file systems of the type 157.Tn NFS 158and 159.Tn NULLFS 160that are listed in the 161.Xr fstab 5 162file. 163.It Fl v 164Verbose, additional information is printed out as each file system 165is unmounted. 166.El 167.Sh ENVIRONMENT 168.Bl -tag -width ".Ev PATH_FSTAB" 169.It Ev PATH_FSTAB 170If the environment variable 171.Ev PATH_FSTAB 172is set, all operations are performed against the specified file. 173.Ev PATH_FSTAB 174will not be honored if the process environment or memory address space is 175considered 176.Dq tainted . 177(See 178.Xr issetugid 2 179for more information.) 180.El 181.Sh FILES 182.Bl -tag -width /etc/fstab -compact 183.It Pa /etc/fstab 184file system table 185.El 186.Sh SEE ALSO 187.Xr unmount 2 , 188.Xr fstab 5 , 189.Xr autounmountd 8 , 190.Xr mount 8 , 191.Xr mdconfig 8 192.Sh HISTORY 193A 194.Nm 195utility appeared in 196.At v1 . 197