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 June 19, 2020 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 56.Pq Ar rhost Ns Cm \& : Ns Ar path , 57the path to the mount point 58.Ar node 59or by the file system ID 60.Ar fsid 61as reported by 62.Dq mount -v 63when run by root. 64.Pp 65The options are as follows: 66.Bl -tag -width "-F fstab" 67.It Fl a 68All the file systems described in 69.Xr fstab 5 70are unmounted. 71.It Fl A 72All the currently mounted file systems are unmounted, 73except for those mounted at 74.Pa / 75or 76.Pa /dev . 77.It Fl F Ar fstab 78Specify the 79.Pa fstab 80file to use. 81.It Fl f 82The file system is forcibly unmounted. 83Active special devices continue to work, 84but all other files return errors if further accesses are attempted. 85The root file system cannot be forcibly unmounted. 86For NFS, a forced dismount can take up to 1 minute or more to 87complete against an unresponsive server and may throw away 88data not yet written to the server for this case. 89If a process, such as 90.Nm 91without the 92.Fl f 93flag is hung on an 94.Tn NFS 95mount point, use the 96.Fl N 97flag instead. 98Also, doing a forced dismount of an NFSv3 mount when 99.Xr rpc.lockd 8 100is running is unsafe and can result in a crash. 101.It Fl h Ar host 102Only file systems mounted from the specified host will be 103unmounted. 104This option implies the 105.Fl A 106option and, unless otherwise specified with the 107.Fl t 108option, will only unmount 109.Tn NFS 110file systems. 111.It Fl N 112Do a forced dismount of an 113.Tn NFS 114mount point without checking the mount path. 115This option can only be used with the path to the mount point 116.Ar node 117and the path must be specified exactly as it was at mount time. 118This option is useful when a process is hung waiting for an unresponsive 119.Tn NFS 120server while holding a vnode lock on the mounted-on vnode, such that 121.Nm 122with the 123.Fl f 124flag can't complete. 125Using this option can result in a loss of file updates that have not been 126flushed to the 127.Tn NFS 128server. 129.It Fl n 130Unless the 131.Fl f 132is used, the 133.Nm 134will not unmount an active file system. 135It will, however, perform a flush. 136This flag disables this behaviour, preventing the flush 137if there are any files open. 138.It Fl t Ar type 139Is used to indicate the actions should only be taken on 140file systems of the specified type. 141More than one type may be specified in a comma separated list. 142The list of file system types can be prefixed with 143.Dq no 144to specify the file system types for which action should 145.Em not 146be taken. 147For example, the 148.Nm 149command: 150.Bd -literal -offset indent 151umount -a -t nfs,nullfs 152.Ed 153.Pp 154unmounts all file systems of the type 155.Tn NFS 156and 157.Tn NULLFS 158that are listed in the 159.Xr fstab 5 160file. 161.It Fl v 162Verbose, additional information is printed out as each file system 163is unmounted. 164.El 165.Sh ENVIRONMENT 166.Bl -tag -width ".Ev PATH_FSTAB" 167.It Ev PATH_FSTAB 168If the environment variable 169.Ev PATH_FSTAB 170is set, all operations are performed against the specified file. 171.Ev PATH_FSTAB 172will not be honored if the process environment or memory address space is 173considered 174.Dq tainted . 175(See 176.Xr issetugid 2 177for more information.) 178.El 179.Sh FILES 180.Bl -tag -width /etc/fstab -compact 181.It Pa /etc/fstab 182file system table 183.El 184.Sh SEE ALSO 185.Xr unmount 2 , 186.Xr fstab 5 , 187.Xr autounmountd 8 , 188.Xr mount 8 189.Sh HISTORY 190A 191.Nm 192utility appeared in 193.At v1 . 194