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32 .\" @(#)mount.8 8.8 (Berkeley) 6/16/94
33 .\" $FreeBSD: src/sbin/mount/mount.8,v 1.31.2.12 2003/02/23 21:17:42 trhodes Exp $
34 .\" $DragonFly: src/sbin/mount/mount.8,v 1.8 2008/04/23 21:59:22 thomas Exp $
35 .\"
36 .Dd June 10, 2009
37 .Dt MOUNT 8
38 .Os
39 .Sh NAME
40 .Nm mount
41 .Nd mount file systems
42 .Sh SYNOPSIS
43 .Nm
44 .Op Fl adfpruvw
45 .Op Fl o Ar options
46 .Op Fl t Ar type
47 .Nm
48 .Op Fl dfpruvw
49 .Brq Ar special | node
50 .Nm
51 .Op Fl dfpruvw
52 .Op Fl o Ar options
53 .Op Fl t Ar type
54 .Ar special node
55 .Sh DESCRIPTION
56 The
57 .Nm
58 utility calls the
59 .Xr mount 2
60 system call to prepare and graft a
61 .Ar "special device"
62 or the remote node (rhost:path) on to the file system tree at the point
63 .Ar node .
64 If either
65 .Ar special
66 or
67 .Ar node
68 are not provided, the appropriate information is taken from the
69 .Xr fstab 5
70 file.
71 .Pp
72 The system maintains a list of currently mounted file systems.
73 If no arguments are given to
74 .Nm ,
75 this list is printed.
76 .Pp
77 The options are as follows:
78 .Bl -tag -width indent
79 .It Fl a
80 All the filesystems described in
81 .Xr fstab 5
82 are mounted.
83 Exceptions are those marked as
84 .Dq noauto ,
85 excluded by the
86 .Fl t
87 flag (see below), or if they are already mounted (except the
88 root filesystem which is always remounted to preserve
89 traditional single user mode behavior).
90 .It Fl d
91 Causes everything to be done except for the actual system call.
92 This option is useful in conjunction with the
93 .Fl v
94 flag to
95 determine what the
96 .Nm
97 command is trying to do.
98 .It Fl f
99 Forces the revocation of write access when trying to downgrade
100 a filesystem mount status from read-write to read-only.
101 Also
102 forces the R/W mount of an unclean filesystem (dangerous; use with
103 caution).
104 .It Fl o
105 Options are specified with a
106 .Fl o
107 flag followed by a comma separated string of options.
108 If a
109 .Dq no
110 prefix is added or removed from a option name, then meaning is negated.
111 In case of conflicting options being specified, the rightmost option
112 takes effect.
113 The following options are available:
114 .Bl -tag -width indent
115 .It Cm async
116 All
117 .Tn I/O
118 to the file system should be done asynchronously.
119 This is a
120 .Em dangerous
121 flag to set,
122 and should not be used unless you are prepared to recreate the file
123 system should your system crash.
124 .It Cm current
125 When used with the
126 .Fl u
127 flag, this is the same as specifying the options currently in effect for
128 the mounted filesystem.
129 .It Cm force
130 The same as
131 .Fl f ;
132 forces the revocation of write access when trying to downgrade
133 a filesystem mount status from read-write to read-only.
134 Also
135 forces the R/W mount of an unclean filesystem (dangerous; use with caution).
136 .It Cm fstab
137 When used with the
138 .Fl u
139 flag, this is the same as specifying all the options listed in the
140 .Xr fstab 5
141 file for the filesystem.
142 .It Cm noasync
143 Metadata I/O should be done synchronously, while data I/O should be done
144 asynchronously.
145 This is the default.
146 .It Cm noatime
147 Do not update the file access time when reading from a file.
148 This option
149 is useful on filesystems where there are large numbers of files and
150 performance is more critical than updating the file access time (which is
151 rarely ever important).
152 This option is currently only supported on local filesystems.
153 .It Cm noauto
154 This filesystem should be skipped when
155 .Nm
156 is run with the
157 .Fl a
158 flag.
159 .It Cm noclusterr
160 Disable read clustering.
161 .It Cm noclusterw
162 Disable write clustering.
163 .It Cm nodev
164 Do not interpret character or block special devices on the file system.
165 This option is useful for a server that has file systems containing
166 special devices for architectures other than its own.
167 This option is set automatically when the user does not have super-user
168 privileges.
169 .It Cm noexec
170 Do not allow execution of any binaries on the mounted file system.
171 This option is useful for a server that has file systems containing
172 binaries for architectures other than its own.
173 .It Cm nosuid
174 Do not allow set-user-identifier or set-group-identifier bits to take effect.
175 Note: this option is worthless if a public available suid or sgid
176 wrapper like
177 .Xr suidperl 1
178 is installed on your system.
179 It is set automatically when the user does not have super-user privileges.
180 .It Cm nosymfollow
181 Do not follow symlinks
182 on the mounted file system.
183 .It Cm rdonly , ro , norw
184 The same as
185 .Fl r ;
186 mount the file system read-only (even the super-user may not write it).
187 .It Cm sync
188 All
189 .Tn I/O
190 to the file system should be done synchronously.
191 .It Cm suiddir
192 A directory on the mounted filesystem will respond to the SUID bit
193 being set, by setting the owner of any new files to be the same
194 as the owner of the directory.
195 New directories will inherit the bit from their parents.
196 Execute bits are removed from
197 the file, and it will not be given to root.
198 .Pp
199 This feature is designed for use on fileservers serving PC users via
200 ftp, SAMBA, or netatalk.
201 It provides security holes for shell users and as
202 such should not be used on shell machines, especially on home directories.
203 This option requires the SUIDDIR
204 option in the kernel to work.
205 Only
206 .Xr UFS 5
207 filesystems support this option.
208 See
209 .Xr chmod 2
210 for more information.
211 .It Cm update
212 The same as
213 .Fl u ;
214 indicate that the status of an already mounted file system should be changed.
215 .It Cm union
216 Causes the namespace at the mount point to appear as the union
217 of the mounted filesystem root and the existing directory.
218 Lookups will be done in the mounted filesystem first.
219 If those operations fail due to a non-existent file the underlying
220 directory is then accessed.
221 All creates are done in the mounted filesystem.
222 .It Cm ignore
223 Will be ignored by
224 .Xr df 1 .
225 .El
226 .Pp
227 Any additional options specific to a filesystem type that is not
228 one of the internally known types (see the
229 .Fl t
230 option) may be passed as a comma separated list; these options are
231 distinguished by a leading
232 .Dq \&-
233 (dash).
234 Options that take a value are specified using the syntax -option=value.
235 For example, the
236 .Nm
237 command:
238 .Bd -literal -offset indent
239 mount -t mfs -o nosuid,-N,-s=4000 /dev/da0s0b /tmp
240 .Ed
241 .Pp
242 causes
243 .Nm
244 to execute the equivalent of:
245 .Bd -literal -offset indent
246 /sbin/mount_mfs -o nosuid -N -s 4000 /dev/da0s0b /tmp
247 .Ed
248 .Pp
249 Additional options specific to filesystem types
250 which are not internally known
251 (see the description of the
252 .Fl t
253 option below)
254 may be described in the manual pages for the associated
255 .Pa /sbin/mount_ Ns Sy XXX
256 utilities.
257 .It Fl p
258 Print mount information in
259 .Xr fstab 5
260 format.
261 If fstab is missing or if the freq and passno fields are omitted,
262 the default values as described in
263 .Xr fstab 5
264 are used.
265 Implies also the
266 .Fl v
267 option.
268 .It Fl r
269 The file system is to be mounted read-only.
270 Mount the file system read-only (even the super-user may not write it).
271 The same as the
272 .Cm rdonly
273 argument to the
274 .Fl o
275 option.
276 .It Fl t Ar type
277 The argument following the
278 .Fl t
279 is used to indicate the file system type.
280 The type
281 .Cm ufs
282 is the default.
283 The
284 .Fl t
285 option can be used
286 to indicate that the actions should only be taken on
287 filesystems of the specified type.
288 More than one type may be specified in a comma separated list.
289 The list of filesystem types can be prefixed with
290 .Dq no
291 to specify the filesystem types for which action should
292 .Em not
293 be taken.
294 For example, the
295 .Nm
296 command:
297 .Bd -literal -offset indent
298 mount -a -t nonfs,mfs
299 .Ed
300 .Pp
301 mounts all filesystems except those of type
302 .Tn NFS
303 and
304 .Tn MFS .
305 .Pp
306 If the type is not the internally known type,
307 .Cm ufs ,
308 .Nm
309 will attempt to execute a program in
310 .Pa /sbin/mount_ Ns Sy XXX
311 where
312 .Sy XXX
313 is replaced by the type name.
314 For example, nfs filesystems are mounted by the program
315 .Pa /sbin/mount_nfs .
316 .Pp
317 Most filesystems will be dynamically loaded by their
318 .Nm
319 programs
320 if not already present in the kernel, using the
321 .Xr vfsload 3
322 subroutine.
323 Because this mechanism requires writable temporary space,
324 the filesystem type containing
325 .Pa /tmp
326 must be compiled into the kernel, and the filesystems containing
327 .Pa /tmp
328 and
329 .Pa /usr/bin/ld
330 must be listed in
331 .Pa /etc/fstab
332 before any filesystems which might be dynamically loaded.
333 .It Fl u
334 The
335 .Fl u
336 flag indicates that the status of an already mounted file
337 system should be changed.
338 Any of the options discussed above (the
339 .Fl o
340 option)
341 may be changed;
342 also a file system can be changed from read-only to read-write
343 or vice versa.
344 An attempt to change from read-write to read-only will fail if any
345 files on the filesystem are currently open for writing unless the
346 .Fl f
347 flag is also specified.
348 The set of options is determined by applying the options specified
349 in the argument to
350 .Fl o
351 and finally applying the
352 .Fl r
353 or
354 .Fl w
355 option.
356 .It Fl v
357 Verbose mode.
358 .It Fl w
359 The file system object is to be read and write.
360 .El
361 .Sh FILES
362 .Bl -tag -width /etc/fstab -compact
363 .It Pa /etc/fstab
364 file system table
365 .El
366 .Sh DIAGNOSTICS
367 Various, most of them are self-explanatory.
368 .Pp
369 .Dl XXXXX filesystem is not available
370 .Pp
371 The kernel does not support the respective filesystem type.
372 Note that
373 support for a particular filesystem might be provided either on a static
374 (kernel compile-time), or dynamic basis (loaded as a kernel module by
375 .Xr kldload 8 ) .
376 Normally,
377 .Nm
378 or its subprocesses attempt to dynamically load a filesystem module if
379 it has not been configured statically, using
380 .Xr vfsload 3 .
381 In this case, the above error message can also mean that you did not
382 have permission to load the module.
383 .Sh SEE ALSO
384 .Xr df 1 ,
385 .Xr lsvfs 1 ,
386 .Xr mount 2 ,
387 .Xr vfsload 3 ,
388 .Xr UFS 5 ,
389 .Xr devtab 5 ,
390 .Xr fstab 5 ,
391 .Xr kldload 8 ,
392 .Xr mount_cd9660 8 ,
393 .Xr mount_devfs 8 ,
394 .Xr mount_ext2fs 8 ,
395 .Xr mount_fdesc 8 ,
396 .Xr mount_hammer 8 ,
397 .Xr mount_hpfs 8 ,
398 .Xr mount_linprocfs 8 ,
399 .Xr mount_mfs 8 ,
400 .Xr mount_msdos 8 ,
401 .Xr mount_nfs 8 ,
402 .Xr mount_ntfs 8 ,
403 .Xr mount_null 8 ,
404 .Xr mount_nwfs 8 ,
405 .Xr mount_portal 8 ,
406 .Xr mount_procfs 8 ,
407 .Xr mount_smbfs 8 ,
408 .Xr mount_std 8 ,
409 .Xr mount_tmpfs 8 ,
410 .Xr mount_udf 8 ,
411 .Xr mount_union 8 ,
412 .Xr sysctl 8 ,
413 .Xr umount 8
414 .Sh CAVEATS
415 After a successful
416 .Nm ,
417 the permissions on the original mount point determine if
418 .Pa ..\&
419 is accessible from the mounted file system.
420 The minimum permissions for
421 the mount point for traversal across the mount point in both
422 directions to be possible for all users is 0111 (execute for all).
423 .Sh HISTORY
424 A
425 .Nm
426 utility appeared in
427 .At v1 .
428 .Sh BUGS
429 It is possible for a corrupted file system to cause a crash.