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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 ufs | external_type
47 .Nm
48 .Op Fl dfpruvw
49 .Ar special | node
50 .Nm
51 .Op Fl dfpruvw
52 .Op Fl o Ar options
53 .Op Fl t Ar ufs | external_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 In case of conflicting options being specified, the rightmost option
109 takes effect.
110 The following options are available:
111 .Bl -tag -width indent
112 .It Cm async
113 All
114 .Tn I/O
115 to the file system should be done asynchronously.
116 This is a
117 .Em dangerous
118 flag to set,
119 and should not be used unless you are prepared to recreate the file
120 system should your system crash.
121 .It Cm current
122 When used with the
123 .Fl u
124 flag, this is the same as specifying the options currently in effect for
125 the mounted filesystem.
126 .It Cm force
127 The same as
128 .Fl f ;
129 forces the revocation of write access when trying to downgrade
130 a filesystem mount status from read-write to read-only.
131 Also
132 forces the R/W mount of an unclean filesystem (dangerous; use with caution).
133 .It Cm fstab
134 When used with the
135 .Fl u
136 flag, this is the same as specifying all the options listed in the
137 .Xr fstab 5
138 file for the filesystem.
139 .It Cm noasync
140 Metadata I/O should be done synchronously, while data I/O should be done
141 asynchronously.
142 This is the default.
143 .It Cm noatime
144 Do not update the file access time when reading from a file.
145 This option
146 is useful on filesystems where there are large numbers of files and
147 performance is more critical than updating the file access time (which is
148 rarely ever important).
149 This option is currently only supported on local filesystems.
150 .It Cm noauto
151 This filesystem should be skipped when
152 .Nm
153 is run with the
154 .Fl a
155 flag.
156 .It Cm noclusterr
157 Disable read clustering.
158 .It Cm noclusterw
159 Disable write clustering.
160 .It Cm nodev
161 Do not interpret character or block special devices on the file system.
162 This option is useful for a server that has file systems containing
163 special devices for architectures other than its own.
164 This option is set automatically when the user does not have super-user
165 privileges.
166 .It Cm noexec
167 Do not allow execution of any binaries on the mounted file system.
168 This option is useful for a server that has file systems containing
169 binaries for architectures other than its own.
170 .It Cm nosuid
171 Do not allow set-user-identifier or set-group-identifier bits to take effect.
172 Note: this option is worthless if a public available suid or sgid
173 wrapper like
174 .Xr suidperl 1
175 is installed on your system.
176 It is set automatically when the user does not have super-user privileges.
177 .It Cm nosymfollow
178 Do not follow symlinks
179 on the mounted file system.
180 .It Cm rdonly
181 The same as
182 .Fl r ;
183 mount the file system read-only (even the super-user may not write it).
184 .It Cm sync
185 All
186 .Tn I/O
187 to the file system should be done synchronously.
188 .It Cm suiddir
189 A directory on the mounted filesystem will respond to the SUID bit
190 being set, by setting the owner of any new files to be the same
191 as the owner of the directory.
192 New directories will inherit the bit from their parents.
193 Execute bits are removed from
194 the file, and it will not be given to root.
195 .Pp
196 This feature is designed for use on fileservers serving PC users via
197 ftp, SAMBA, or netatalk.
198 It provides security holes for shell users and as
199 such should not be used on shell machines, especially on home directories.
200 This option requires the SUIDDIR
201 option in the kernel to work.
202 Only
203 .Xr UFS 5
204 filesystems support this option.
205 See
206 .Xr chmod 2
207 for more information.
208 .It Cm update
209 The same as
210 .Fl u ;
211 indicate that the status of an already mounted file system should be changed.
212 .It Cm union
213 Causes the namespace at the mount point to appear as the union
214 of the mounted filesystem root and the existing directory.
215 Lookups will be done in the mounted filesystem first.
216 If those operations fail due to a non-existent file the underlying
217 directory is then accessed.
218 All creates are done in the mounted filesystem.
219 .It Cm ignore
220 Will be ignored by
221 .Xr df 1 .
222 .El
223 .Pp
224 Any additional options specific to a filesystem type that is not
225 one of the internally known types (see the
226 .Fl t
227 option) may be passed as a comma separated list; these options are
228 distinguished by a leading
229 .Dq \&-
230 (dash).
231 Options that take a value are specified using the syntax -option=value.
232 For example, the
233 .Nm
234 command:
235 .Bd -literal -offset indent
236 mount -t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp
237 .Ed
238 .Pp
239 causes
240 .Nm
241 to execute the equivalent of:
242 .Bd -literal -offset indent
243 /sbin/mount_mfs -o nosuid -N -s 4000 /dev/dk0b /tmp
244 .Ed
245 .Pp
246 Additional options specific to filesystem types
247 which are not internally known
248 (see the description of the
249 .Fl t
250 option below)
251 may be described in the manual pages for the associated
252 .Pa /sbin/mount_ Ns Sy XXX
253 utilities.
254 .It Fl p
255 Print mount information in
256 .Xr fstab 5
257 format.
258 If fstab is missing or if the freq and passno fields are omitted,
259 the default values as described in
260 .Xr fstab 5
261 are used.
262 Implies also the
263 .Fl v
264 option.
265 .It Fl r
266 The file system is to be mounted read-only.
267 Mount the file system read-only (even the super-user may not write it).
268 The same as the
269 .Cm rdonly
270 argument to the
271 .Fl o
272 option.
273 .It Fl t Ar ufs | external_type
274 The argument following the
275 .Fl t
276 is used to indicate the file system type.
277 The type
278 .Ar ufs
279 is the default.
280 The
281 .Fl t
282 option can be used
283 to indicate that the actions should only be taken on
284 filesystems of the specified type.
285 More than one type may be specified in a comma separated list.
286 The list of filesystem types can be prefixed with
287 .Dq no
288 to specify the filesystem types for which action should
289 .Em not
290 be taken.
291 For example, the
292 .Nm
293 command:
294 .Bd -literal -offset indent
295 mount -a -t nonfs,mfs
296 .Ed
297 .Pp
298 mounts all filesystems except those of type
299 .Tn NFS
300 and
301 .Tn MFS .
302 .Pp
303 If the type is not one of the internally known types,
304 .Nm
305 will attempt to execute a program in
306 .Pa /sbin/mount_ Ns Sy XXX
307 where
308 .Sy XXX
309 is replaced by the type name.
310 For example, nfs filesystems are mounted by the program
311 .Pa /sbin/mount_nfs .
312 .Pp
313 Most filesystems will be dynamically loaded by their
314 .Nm
315 programs
316 if not already present in the kernel, using the
317 .Xr vfsload 3
318 subroutine.
319 Because this mechanism requires writable temporary space,
320 the filesystem type containing
321 .Pa /tmp
322 must be compiled into the kernel, and the filesystems containing
323 .Pa /tmp
324 and
325 .Pa /usr/bin/ld
326 must be listed in
327 .Pa /etc/fstab
328 before any filesystems which might be dynamically loaded.
329 .It Fl u
330 The
331 .Fl u
332 flag indicates that the status of an already mounted file
333 system should be changed.
334 Any of the options discussed above (the
335 .Fl o
336 option)
337 may be changed;
338 also a file system can be changed from read-only to read-write
339 or vice versa.
340 An attempt to change from read-write to read-only will fail if any
341 files on the filesystem are currently open for writing unless the
342 .Fl f
343 flag is also specified.
344 The set of options is determined by applying the options specified
345 in the argument to
346 .Fl o
347 and finally applying the
348 .Fl r
349 or
350 .Fl w
351 option.
352 .It Fl v
353 Verbose mode.
354 .It Fl w
355 The file system object is to be read and write.
356 .El
357 .Sh FILES
358 .Bl -tag -width /etc/fstab -compact
359 .It Pa /etc/fstab
360 file system table
361 .El
362 .Sh DIAGNOSTICS
363 Various, most of them are self-explanatory.
364 .Pp
365 .Dl XXXXX filesystem is not available
366 .Pp
367 The kernel does not support the respective filesystem type.
368 Note that
369 support for a particular filesystem might be provided either on a static
370 (kernel compile-time), or dynamic basis (loaded as a kernel module by
371 .Xr kldload 8 ) .
372 Normally,
373 .Nm
374 or its subprocesses attempt to dynamically load a filesystem module if
375 it has not been configured statically, using
376 .Xr vfsload 3 .
377 In this case, the above error message can also mean that you did not
378 have permission to load the module.
379 .Sh SEE ALSO
380 .Xr df 1 ,
381 .Xr lsvfs 1 ,
382 .Xr mount 2 ,
383 .Xr vfsload 3 ,
384 .Xr fstab 5 ,
385 .Xr kldload 8 ,
386 .Xr mount_cd9660 8 ,
387 .Xr mount_ext2fs 8 ,
388 .Xr mount_fdesc 8 ,
389 .Xr mount_hammer 8 ,
390 .Xr mount_linprocfs 8 ,
391 .Xr mount_mfs 8 ,
392 .Xr mount_msdos 8 ,
393 .Xr mount_nfs 8 ,
394 .Xr mount_ntfs 8 ,
395 .Xr mount_null 8 ,
396 .Xr mount_nwfs 8 ,
397 .Xr mount_portal 8 ,
398 .Xr mount_procfs 8 ,
399 .Xr mount_smbfs 8 ,
400 .Xr mount_std 8 ,
401 .Xr mount_udf 8 ,
402 .Xr mount_union 8 ,
403 .Xr sysctl 8 ,
404 .Xr umount 8
405 .Sh CAVEATS
406 After a successful
407 .Nm ,
408 the permissions on the original mount point determine if
409 .Pa ..\&
410 is accessible from the mounted file system.
411 The minimum permissions for
412 the mount point for traversal across the mount point in both
413 directions to be possible for all users is 0111 (execute for all).
414 .Sh HISTORY
415 A
416 .Nm
417 utility appeared in
418 .At v1 .
419 .Sh BUGS
420 It is possible for a corrupted file system to cause a crash.