1.\" Copyright (c) 1980, 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)mount.8 8.4 (Berkeley) 02/20/94 7.\" 8.Dd 9.Dt MOUNT 8 10.Os BSD 4 11.Sh NAME 12.Nm mount 13.Nd mount file systems 14.Sh SYNOPSIS 15.Nm mount 16.Op Fl adfruvw 17.Op Fl t Ar ufs | lfs | external_type 18.Nm mount 19.Op Fl dfruvw 20.Ar special | node 21.Nm mount 22.Op Fl dfruvw 23.Op Fl t Ar ufs | lfs | external_type 24.Op Fl o Ar options 25.Ar special node 26.Sh DESCRIPTION 27The 28.Nm mount 29command 30calls the 31.Xr mount 2 32system call to prepare and graft a 33.Ar "special device" 34or the remote node (rhost:path) on to the file system tree at the point 35.Ar node . 36If either 37.Ar special 38or 39.Ar node 40are not provided, the appropriate information is taken from the 41.Xr fstab 5 42file. 43.Pp 44The system maintains a list of currently mounted file systems. 45If no arguments are given to 46.Nm mount, 47this list is printed. 48.Pp 49The options are as follows: 50.Bl -tag -width indent 51.It Fl F 52The standard mount options are parsed and 53passed to external program via the 54.Fl F 55option 56as a decimal number. 57(See example below.) 58.It Fl d 59Causes everything to be done except for the actual system call. 60This option is useful in conjunction with the 61.Fl v 62flag to 63determine what the 64.Nm mount 65command is trying to do. 66.It Fl f 67Forces the revocation of write access when trying to downgrade 68a filesystem mount status from read-write to read-only. 69.It Fl o 70Options are specified with a 71.Fl o 72flag 73followed by a comma separated string of options. 74The following options apply to any file system that is being mounted: 75.Bl -tag -width indent 76.It noexec 77Do not allow execution of any binaries on the mounted file system. 78This option is useful for a server that has file systems containing 79binaries for architectures other than its own. 80.It nosuid 81Do not allow set-user-identifier or set-group-identifier bits to take effect. 82.It nodev 83Do not interpret character or block special devices on the file system. 84This option is useful for a server that has file systems containing 85special devices for architectures other than its own. 86.It synchronous 87All 88.Tn I/O 89to the file system should be done synchronously. 90.It union 91Causes the namespace at the mount point to appear as the union 92of the mounted filesystem root and the existing directory. 93Lookups will be done in the mounted filesystem first. 94If those operations fail due to a non-existent file the underlying 95directory is then accessed. 96All creates are done in the mounted filesystem. 97.El 98.It Fl r 99The file system object is to be mounted read-only. 100.It Fl t Ar "ufs \\*(Ba lfs \\*(Ba external type" 101The argument following the 102.Fl t 103is used to indicate the file system type. 104The type 105.Ar ufs 106is the default. 107The \fI-t\fP option can be used 108to indicate that the actions should only be taken on 109filesystems of the specified type. 110More than one type may be specified in a comma separated list. 111The list of filesystem types can be prefixed with 112.Dq no 113to specify the filesystem types for which action should 114.Em not 115be taken. 116For example, the 117.Nm mount 118command: 119.Bd -literal -offset indent 120mount -a -t nonfs,mfs 121.Ed 122.Pp 123mounts all filesystems except those of type 124.Tn NFS 125and 126.Tn MFS . 127.Pp 128If the type is not one of the internally known types, 129mount will attempt to execute a program in 130.Pa /sbin/mount_ Ns Em XXX 131where 132.Em XXX 133is replaced by the type name. 134For example, nfs filesystems are mounted by the program 135.Pa /sbin/mount_nfs . 136.It Fl u 137The 138.Fl u 139flag indicates that the status of an already mounted file 140system should be changed. 141Any of the options discussed above (the 142.Fl o 143option) 144may be changed; 145also a file system can be changed from read-only to read-write 146or vice versa. 147An attempt to change from read-write to read-only will fail if any 148files on the filesystem are currently open for writing unless the 149.Fl f 150flag is also specified. 151The set of options is determined by first extracting the options 152for the file system from the 153.Xr fstab 154table, 155then applying any options specified by the 156.Fl o 157argument, 158and finally applying the 159.Fl r 160or 161.Fl w 162option. 163.It Fl v 164Verbose mode. 165.It Fl w 166The file system object is to be read and write. 167.It Fl 168Any additional options specific to the program can 169be passed as a comma separated list; 170these options are distinguished by starting with a 171.Fl 172(dash). 173.El 174.Pp 175Those options that take a value are specified 176using the syntax -option=value. 177For example, the mount command: 178.Bd -literal -offset indent 179mount -t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp 180.Ed 181.Pp 182causes mount to attempt to execute: 183.Bd -literal -offset indent 184/sbin/mount_mfs -F 8 -N -s 4000 /dev/dk0b /tmp 185.Ed 186.Pp 187The options specific to NFS filesystems are described in the 188.Xr mount_nfs 8 189manual page. 190.Sh FILES 191.Bl -tag -width /etc/fstab -compact 192.It Pa /etc/fstab 193file system table 194.El 195.Sh SEE ALSO 196.Xr mount 2 , 197.Xr fstab 5 , 198.Xr mount_cd9660 8 , 199.Xr mount_fdesc 8 , 200.Xr mount_kernfs 8 , 201.Xr mount_lfs 8 , 202.Xr mount_lofs 8 , 203.Xr mount_mfs 8 , 204.Xr mount_nfs 8 , 205.Xr mount_null 8 , 206.Xr mount_portal 8 , 207.Xr mount_procfs 8 , 208.Xr mount_umap 8 , 209.Xr mount_union 8 , 210.Xr umount 8 211.Sh BUGS 212It is possible for a corrupted file system to cause a crash. 213.Sh HISTORY 214A 215.Nm mount 216command appeared in 217.At v6 . 218