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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)mount.8 8.8 (Berkeley) 6/16/94 33.\" $Id: mount.8,v 1.23 1998/07/09 05:49:58 jkoshy Exp $ 34.\" 35.Dd June 16, 1994 36.Dt MOUNT 8 37.Os BSD 4 38.Sh NAME 39.Nm mount 40.Nd mount file systems 41.Sh SYNOPSIS 42.Nm mount 43.Op Fl adfpruvw 44.Op Fl t Ar ufs | lfs | external_type 45.Nm mount 46.Op Fl dfpruvw 47.Ar special | node 48.Nm mount 49.Op Fl dfpruvw 50.Op Fl o Ar options 51.Op Fl t Ar ufs | lfs | external_type 52.Ar special node 53.Sh DESCRIPTION 54The 55.Nm 56command 57calls the 58.Xr mount 2 59system call to prepare and graft a 60.Ar "special device" 61or the remote node (rhost:path) on to the file system tree at the point 62.Ar node . 63If either 64.Ar special 65or 66.Ar node 67are not provided, the appropriate information is taken from the 68.Xr fstab 5 69file. 70.Pp 71The system maintains a list of currently mounted file systems. 72If no arguments are given to 73.Nm mount , 74this list is printed. 75.Pp 76The options are as follows: 77.Bl -tag -width indent 78.It Fl a 79All the filesystems described in 80.Xr fstab 5 81are mounted. 82Exceptions are those marked as ``noauto'', excluded by the 83.Fl t 84flag (see below), or if they are already mounted (except the 85root filesystem which is always remounted to preserve 86traditional single user mode behavior). 87.It Fl d 88Causes everything to be done except for the actual system call. 89This option is useful in conjunction with the 90.Fl v 91flag to 92determine what the 93.Nm 94command is trying to do. 95.It Fl f 96Forces the revocation of write access when trying to downgrade 97a filesystem mount status from read-write to read-only. Also 98forces the R/W mount of an unclean filesystem (dangerous; use with 99caution). 100.It Fl o 101Options are specified with a 102.Fl o 103flag followed by a comma separated string of options. 104The following options are available: 105.Bl -tag -width indent 106.It async 107All 108.Tn I/O 109to the file system should be done asynchronously. 110This is a 111.Em dangerous 112flag to set, 113and should not be used unless you are prepared to recreate the file 114system should your system crash. 115.It force 116The same as 117.Fl f ; 118forces the revocation of write access when trying to downgrade 119a filesystem mount status from read-write to read-only. Also 120forces the R/W mount of an unclean filesystem (dangerous; use with caution). 121.It noatime 122Do not update the file access time when reading from a file. This option 123is useful on filesystems where there are large numbers of files and 124performance is more critical than updating the file access time (which is 125rarely ever important). This option is currently only supported on local 126filesystems. 127.It noauto 128This filesystem should be skipped when mount is run with the 129.Fl a 130flag. 131.It noclusterr 132Disable read clustering. 133.It noclusterw 134Disable write clustering. 135.It nodev 136Do not interpret character or block special devices on the file system. 137This option is useful for a server that has file systems containing 138special devices for architectures other than its own. 139.It noexec 140Do not allow execution of any binaries on the mounted file system. 141This option is useful for a server that has file systems containing 142binaries for architectures other than its own. 143.It nosuid 144Do not allow set-user-identifier or set-group-identifier bits to take effect. 145Note: this option is worthless if a public available suid or sgid 146wrapper like 147.Xr suidperl 1 148is installed on your system. 149.It nosymfollow 150Do not follow symlinks 151on the mounted file system. 152.It rdonly 153The same as 154.Fl r ; 155mount the file system read-only (even the super-user may not write it). 156.It sync 157All 158.Tn I/O 159to the file system should be done synchronously. 160.It suiddir 161A directory on the mounted filesystem will respond to the SUID bit 162being set, by setting the owner of any new files to be the same 163as the owner of the directory. 164New directories will inherit the bit from their parents. 165Execute bits are removed from 166the file, and it will not be given to root. 167.Pp 168This feature is designed for use on fileservers serving PC users via 169ftp, SAMBA, or netatalk. It provides security holes for shell users and as 170such should not be used on shell machines, especially on home directories. 171This option requires the SUIDDIR 172option in the kernel to work. Only UFS filesystems support this option. 173See 174.Xr chmod 2 175for more information. 176.It update 177The same as 178.Fl u ; 179indicate that the status of an already mounted file system should be changed. 180.It union 181Causes the namespace at the mount point to appear as the union 182of the mounted filesystem root and the existing directory. 183Lookups will be done in the mounted filesystem first. 184If those operations fail due to a non-existent file the underlying 185directory is then accessed. 186All creates are done in the mounted filesystem. 187.El 188.Pp 189Any additional options specific to a filesystem type that is not 190one of the internally known types (see the 191.Fl t 192option) may be passed as a comma separated list; these options are 193distinguished by a leading 194.Dq \&- 195(dash). 196Options that take a value are specified using the syntax -option=value. 197For example, the 198.Nm 199command: 200.Bd -literal -offset indent 201mount -t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp 202.Ed 203.Pp 204causes 205.Nm 206to execute the equivalent of: 207.Bd -literal -offset indent 208/sbin/mount_mfs -o nosuid -N -s 4000 /dev/dk0b /tmp 209.Ed 210.It Fl p 211Print mount information in fstab format. Implies also the 212.Fl v 213option. 214.It Fl r 215The file system is to be mounted read-only. 216Mount the file system read-only (even the super-user may not write it). 217The same as the 218.Dq rdonly 219argument to the 220.Fl o 221option. 222.It Fl t Ar "ufs \\*(Ba lfs \\*(Ba external type" 223The argument following the 224.Fl t 225is used to indicate the file system type. 226The type 227.Ar ufs 228is the default. 229The 230.Fl t 231option can be used 232to indicate that the actions should only be taken on 233filesystems of the specified type. 234More than one type may be specified in a comma separated list. 235The list of filesystem types can be prefixed with 236.Dq no 237to specify the filesystem types for which action should 238.Em not 239be taken. 240For example, the 241.Nm 242command: 243.Bd -literal -offset indent 244mount -a -t nonfs,mfs 245.Ed 246.Pp 247mounts all filesystems except those of type 248.Tn NFS 249and 250.Tn MFS . 251.Pp 252If the type is not one of the internally known types, 253.Nm 254will attempt to execute a program in 255.Pa /sbin/mount_ Ns Em XXX 256where 257.Em XXX 258is replaced by the type name. 259For example, nfs filesystems are mounted by the program 260.Pa /sbin/mount_nfs . 261.Pp 262Most filesystems will be dynamically loaded by their mount programs 263if not already present in the kernel, using the 264.Xr vfsload 3 265subroutine. Because this mechanism requires writable temporary space, 266the filesystem type containing 267.Pa /tmp 268must be compiled into the kernel, and the filesystems containing 269.Pa /tmp 270and 271.Pa /usr/bin/ld 272must be listed in 273.Pa /etc/fstab 274before any filesystems which might be dynamically loaded. 275.It Fl u 276The 277.Fl u 278flag indicates that the status of an already mounted file 279system should be changed. 280Any of the options discussed above (the 281.Fl o 282option) 283may be changed; 284also a file system can be changed from read-only to read-write 285or vice versa. 286An attempt to change from read-write to read-only will fail if any 287files on the filesystem are currently open for writing unless the 288.Fl f 289flag is also specified. 290The set of options is determined by first extracting the options 291for the file system from the 292.Xr fstab 5 293table, 294then applying any options specified by the 295.Fl o 296argument, 297and finally applying the 298.Fl r 299or 300.Fl w 301option. 302.It Fl v 303Verbose mode. 304.It Fl w 305The file system object is to be read and write. 306.Pp 307The options specific to NFS filesystems are described in the 308.Xr mount_nfs 8 309manual page. 310.Sh DIAGNOSTICS 311Various, most of them are self-explanatory. 312.Pp 313.Dl XXXXX filesystem is not available 314.Pp 315The kernel doesn't support the respective filesystem type. Note that 316support for a particular filesystem might be provided either on a static 317(kernel compile-time), or dynamic basis (loaded as a kernel module by 318.Xr modload 8 ). 319Normally, 320.Nm 321or its subprocesses attempt to dynamically load a filesystem module if 322it hasn't been configured statically, using 323.Xr vfsload 3 . 324In this case, the above error message can also mean that you didn't 325have permission to load the module. 326.Sh FILES 327.Bl -tag -width /etc/fstab -compact 328.It Pa /etc/fstab 329file system table 330.El 331.Sh SEE ALSO 332.Xr mount 2 , 333.Xr vfsload 3 , 334.Xr fstab 5 , 335.Xr mount_cd9660 8 , 336.Xr mount_devfs 8 , 337.Xr mount_fdesc 8 , 338.Xr mount_kernfs 8 , 339.Xr mount_lfs 8 , 340.Xr mount_mfs 8 , 341.Xr mount_msdos 8 , 342.Xr mount_nfs 8 , 343.Xr mount_null 8 , 344.Xr mount_portal 8 , 345.Xr mount_procfs 8 , 346.Xr mount_umap 8 , 347.Xr mount_union 8 , 348.Xr umount 8 349.Sh BUGS 350It is possible for a corrupted file system to cause a crash. 351.Pp 352Switching a filesystem back and forth between asynchronous and normal 353operation or between read/write and read/only access using ``mount 354-u'' may gradually bring about severe filesystem corruption. 355.Sh CAVEATS 356After a successful mount, the permissions on the original mount point 357determine if 358.Pa ".." 359is accessible from the mounted file system. The minimum permissions for 360the mount point for traversal across the mount point in both 361directions to be possible for all users is 0111 (execute for all). 362.Sh HISTORY 363A 364.Nm 365command appeared in 366.At v1 . 367