1.\" $OpenBSD: mount.8,v 1.66 2009/06/04 13:30:06 jmc Exp $ 2.\" $NetBSD: mount.8,v 1.11 1995/07/12 06:23:21 cgd Exp $ 3.\" 4.\" Copyright (c) 1980, 1989, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)mount.8 8.7 (Berkeley) 3/27/94 32.\" 33.Dd $Mdocdate: June 4 2009 $ 34.Dt MOUNT 8 35.Os 36.Sh NAME 37.Nm mount 38.Nd mount file systems 39.Sh SYNOPSIS 40.Nm mount 41.Op Fl Aadfruvw 42.Op Fl t Ar type 43.Nm mount 44.Op Fl dfrsuvw 45.Ar special | node 46.Nm mount 47.Op Fl dfruvw 48.Op Fl o Ar options 49.Op Fl t Ar type 50.Ar special node 51.Sh DESCRIPTION 52The 53.Nm 54command invokes a file system specific program to prepare 55and graft the 56.Ar special 57device or remote node (rhost:path) on to the file system 58tree at the point 59.Ar node . 60If either 61.Ar special 62or 63.Ar node 64are not provided, the appropriate information is taken from the 65.Xr fstab 5 66file. 67.Pp 68For disk partitions, the 69.Ar special 70device must correspond to a partition registered in the 71.Xr disklabel 5 . 72.Pp 73The system maintains a list of currently mounted file systems. 74If no arguments are given to 75.Nm mount , 76this list is printed. 77.Pp 78A mount point 79.Ar node 80must be an existing directory for a mount to succeed 81.Po 82except in the special case of 83.Pa / , 84of course 85.Pc . 86Only the superuser may mount file systems unless 87.Va kern.usermount 88is nonzero 89.Po 90see 91.Xr sysctl 8 92.Pc , 93the 94.Ar special 95device 96is readable and writeable by the user attempting the mount, 97and the mount point 98.Ar node 99is owned by the user attempting the mount. 100.Pp 101The options are as follows: 102.Bl -tag -width Ds 103.It Fl A 104Causes 105.Nm 106to try to mount all of the file systems listed in the 107.Xr fstab 5 108table except those for which the 109.Dq noauto 110option is specified. 111.It Fl a 112Similar to the 113.Fl A 114flag, except that if a file system (other than the root file system) 115appears to be already mounted, 116.Nm 117will not try to mount it again. 118.Nm 119assumes that a file system is already mounted if a file system with 120the same type is mounted on the given mount point. 121More stringent checks are not possible because some file system types 122report strange values for the mounted-from device for mounted file 123systems. 124.It Fl d 125Causes everything to be done except for the invocation of 126the file system specific program. 127This option is useful in conjunction with the 128.Fl v 129flag to 130determine what the 131.Nm 132command is trying to do. 133.It Fl f 134Either force mounting of dirty file systems or, in the case of a 135downgrade from read-write to read-only operation, the revocation of 136opened files with write access. 137.It Fl o Ar options 138Options can be given with (or without) a 139.Sq no 140prefix to invert their meaning. 141The options listed below specify non-default values. 142For example, 143.Sq nosoftdep 144is the default, so 145.Sq softdep 146can be used to mount the file system using soft dependencies. 147Multiple options can be specified in a comma-separated list. 148The available options are as follows: 149.Bl -tag -width Ds 150.It async 151Metadata I/O to the file system should be done asynchronously. 152By default, only regular data is read/written asynchronously. 153.Pp 154This is a 155.Em dangerous 156flag to set since it does not guarantee to keep a consistent 157file system structure on the disk. 158You should not use this flag 159unless you are prepared to recreate the file system should your 160system crash. 161The most common use of this flag is to speed up 162.Xr restore 8 163where it can give a factor of two speed increase. 164.Pp 165The options 166.Ic async 167and 168.Ic softdep 169are mutually exclusive. 170.It force 171The same as 172.Fl f ; 173forces the revocation of write access when trying to downgrade 174a file system mount status from read-write to read-only. 175.It noatime 176Do not update atime on files in the system unless the mtime or ctime 177is being changed as well. 178This option is useful for laptops and news servers where one does 179not want the extra disk activity associated with updating the atime. 180.It noauto 181Do not mount the file system automatically 182(either at boot or with the 183.Fl A 184or 185.Fl a 186options). 187.It noaccesstime 188Synonym for noatime provided for compatibility with 189other operating systems. 190.It nodev 191Do not interpret character or block special devices on the file system. 192This option is useful for a server that has file systems containing 193special devices for architectures other than its own. 194.It noexec 195Do not allow execution of any binaries on the mounted file system. 196This option is useful for a server that has file systems containing 197binaries for architectures other than its own. 198.It nosuid 199Do not allow set-user-identifier or set-group-identifier bits to take effect. 200.It rdonly 201The same as 202.Fl r ; 203mount the file system read-only (even the superuser may not write it). 204.It softdep 205(FFS only.) 206Mount the file system using soft dependencies. 207Instead of metadata being written immediately, it is written in an ordered 208fashion to keep the on-disk state of the file system consistent. 209This results in significant speedups for file create/delete operations. 210This option is ignored when using the 211.Fl u 212flag and a file system is already mounted read/write. 213.Pp 214The options 215.Ic async 216and 217.Ic softdep 218are mutually exclusive. 219.It sync 220Regular data I/O to the file system should be done synchronously. 221By default, only metadata is read/written synchronously. 222.Pp 223.It update 224The same as 225.Fl u ; 226indicate that the status of an already mounted file system should be changed. 227.El 228.Pp 229Any additional options specific to a given file system type (see the 230.Fl t 231option) may be passed as a comma separated list; these options are 232distinguished by a leading 233.Dq \&- 234(dash). 235Options that take a value are specified using the syntax -option=value. 236For example: 237.Bd -literal -offset 3n 238# mount -t mfs -o rw,nodev,nosuid,-s=153600 /dev/sd0b /tmp 239.Ed 240.Pp 241That causes 242.Nm 243to execute the equivalent of: 244.Bd -literal -offset 3n 245# /sbin/mount_mfs -o rw,nodev,nosuid -s 153600 /dev/sd0b /tmp 246.Ed 247.Pp 248The equivalent example in 249.Xr fstab 5 250would be: 251.Bd -literal -offset 3n 252swap /tmp mfs rw,nodev,nosuid,-s=153600 0 0 253.Ed 254.It Fl r 255The file system is to be mounted read-only. 256Mount the file system read-only (even the superuser may not write it). 257The same as the 258.Dq rdonly 259argument to the 260.Fl o 261option. 262.It Fl s 263Skip mounting the file system if it is already mounted. 264See the 265.Fl a 266flag for a description of the criteria used to decide if a file system 267is already mounted. 268.It Fl t Ar type 269The argument following the 270.Fl t 271is used to indicate the file system type. 272The type 273.Ar ffs 274is the default. 275The 276.Fl t 277option can be used 278to indicate that the actions should only be taken on 279file systems of the specified type. 280More than one type may be specified in a comma separated list. 281The list of file system types can be prefixed with 282.Dq no 283to specify the file system types for which action should 284.Em not 285be taken. 286For example, the 287.Nm 288command: 289.Bd -literal -offset indent 290# mount -a -t nonfs,mfs 291.Ed 292.Pp 293mounts all file systems except those of type NFS and MFS . 294.Pp 295.Nm 296will attempt to execute a program in 297.Pa /sbin/mount_ Ns Em XXX 298where 299.Em XXX 300is replaced by the type name. 301For example, NFS file systems are mounted by the program 302.Pa /sbin/mount_nfs . 303.It Fl u 304The 305.Fl u 306flag indicates that the status of an already mounted file 307system should be changed. 308Any of the options discussed above (the 309.Fl o 310option) 311may be changed; 312also a file system can be changed from read-only to read-write 313or vice versa. 314An attempt to change from read-write to read-only will fail if any 315files on the file system are currently open for writing unless the 316.Fl f 317flag is also specified. 318Only options specified on the command line with 319.Fl o 320are changed; 321other file system options are unaltered. 322The options set in the 323.Xr fstab 5 324table are ignored. 325.It Fl v 326Verbose mode. 327.It Fl w 328The file system object is to be read and write. 329.El 330.Pp 331The options specific to the various file system types are 332described in the manual pages for those file systems' 333.Nm mount_XXX 334commands. 335For instance, the options specific to Berkeley 336Fast File Systems are described in the 337.Xr mount_ffs 8 338manual page. 339.Sh FILES 340.Bl -tag -width /etc/fstab -compact 341.It Pa /etc/fstab 342file system table 343.El 344.Sh EXAMPLES 345Mount a CD-ROM on node 346.Pa /mnt/cdrom : 347.Pp 348.Dl # mount -t cd9660 -r /dev/cd0a /mnt/cdrom 349.Pp 350Mount an MS-DOS floppy on node 351.Pa /mnt/floppy : 352.Pp 353.Dl # mount -t msdos /dev/fd0a /mnt/floppy 354.Pp 355Graft a remote NFS file system on host 356.Ar host , 357path 358.Pa /path/name , 359on node 360.Pa /mnt/nfs : 361.Pp 362.Dl # mount host:/path/name /mnt/nfs 363.Pp 364Remount 365.Pa /var 366with option 367.Dq dev : 368.Pp 369.Dl # mount -u -o dev /var 370.Sh SEE ALSO 371.Xr mount 2 , 372.Xr fstab 5 , 373.Xr disklabel 8 , 374.Xr mount_cd9660 8 , 375.Xr mount_ext2fs 8 , 376.Xr mount_ffs 8 , 377.Xr mount_mfs 8 , 378.Xr mount_msdos 8 , 379.Xr mount_nfs 8 , 380.Xr mount_nnpfs 8 , 381.Xr mount_ntfs 8 , 382.Xr mount_portal 8 , 383.Xr mount_procfs 8 , 384.Xr mount_udf 8 , 385.Xr mount_vnd 8 , 386.Xr sysctl 8 , 387.Xr umount 8 388.Sh HISTORY 389A 390.Nm 391command appeared in 392.At v3 . 393.Sh CAVEATS 394After a successful 395.Nm mount , 396the permissions on the original mount point determine if 397.Dq \&.\&. 398is accessible from the mounted file system. 399The minimum permissions for 400the mount point for traversal across the mount point in both 401directions to be possible for all users is 0111 (execute for all). 402