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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 1.2 2003/06/17 04:27:33 dillon Exp $
41 .Nd mount file systems
45 .Op Fl t Ar ufs | external_type
52 .Op Fl t Ar ufs | external_type
59 system call to prepare and graft a
61 or the remote node (rhost:path) on to the file system tree at the point
67 are not provided, the appropriate information is taken from the
71 The system maintains a list of currently mounted file systems.
72 If no arguments are given to
76 The options are as follows:
77 .Bl -tag -width indent
79 All the filesystems described in
82 Exceptions are those marked as
86 flag (see below), or if they are already mounted (except the
87 root filesystem which is always remounted to preserve
88 traditional single user mode behavior).
90 Causes everything to be done except for the actual system call.
91 This option is useful in conjunction with the
96 command is trying to do.
98 Forces the revocation of write access when trying to downgrade
99 a filesystem mount status from read-write to read-only.
101 forces the R/W mount of an unclean filesystem (dangerous; use with
104 Options are specified with a
106 flag followed by a comma separated string of options.
107 In case of conflicting options being specified, the rightmost option
109 The following options are available:
110 .Bl -tag -width indent
114 to the file system should be done asynchronously.
118 and should not be used unless you are prepared to recreate the file
119 system should your system crash.
123 flag, this is the same as specifying the options currently in effect for
124 the mounted filesystem.
128 forces the revocation of write access when trying to downgrade
129 a filesystem mount status from read-write to read-only.
131 forces the R/W mount of an unclean filesystem (dangerous; use with caution).
135 flag, this is the same as specifying all the options listed in the
137 file for the filesystem.
139 Metadata I/O should be done synchronously, while data I/O should be done
143 Do not update the file access time when reading from a file.
145 is useful on filesystems where there are large numbers of files and
146 performance is more critical than updating the file access time (which is
147 rarely ever important).
148 This option is currently only supported on local filesystems.
150 This filesystem should be skipped when
156 Disable read clustering.
158 Disable write clustering.
160 Do not interpret character or block special devices on the file system.
161 This option is useful for a server that has file systems containing
162 special devices for architectures other than its own.
163 This option is set automatically when the user does not have super-user
166 Do not allow execution of any binaries on the mounted file system.
167 This option is useful for a server that has file systems containing
168 binaries for architectures other than its own.
170 Do not allow set-user-identifier or set-group-identifier bits to take effect.
171 Note: this option is worthless if a public available suid or sgid
174 is installed on your system.
175 It is set automatically when the user does not have super-user privileges.
177 Do not follow symlinks
178 on the mounted file system.
182 mount the file system read-only (even the super-user may not write it).
186 to the file system should be done synchronously.
188 A directory on the mounted filesystem will respond to the SUID bit
189 being set, by setting the owner of any new files to be the same
190 as the owner of the directory.
191 New directories will inherit the bit from their parents.
192 Execute bits are removed from
193 the file, and it will not be given to root.
195 This feature is designed for use on fileservers serving PC users via
196 ftp, SAMBA, or netatalk.
197 It provides security holes for shell users and as
198 such should not be used on shell machines, especially on home directories.
199 This option requires the SUIDDIR
200 option in the kernel to work.
201 Only UFS filesystems support this option.
204 for more information.
208 indicate that the status of an already mounted file system should be changed.
210 Causes the namespace at the mount point to appear as the union
211 of the mounted filesystem root and the existing directory.
212 Lookups will be done in the mounted filesystem first.
213 If those operations fail due to a non-existent file the underlying
214 directory is then accessed.
215 All creates are done in the mounted filesystem.
218 Any additional options specific to a filesystem type that is not
219 one of the internally known types (see the
221 option) may be passed as a comma separated list; these options are
222 distinguished by a leading
225 Options that take a value are specified using the syntax -option=value.
229 .Bd -literal -offset indent
230 mount -t mfs -o nosuid,-N,-s=4000 /dev/dk0b /tmp
235 to execute the equivalent of:
236 .Bd -literal -offset indent
237 /sbin/mount_mfs -o nosuid -N -s 4000 /dev/dk0b /tmp
240 Additional options specific to filesystem types
241 which are not internally known
242 (see the description of the
245 may be described in the manual pages for the associated
246 .Pa /sbin/mount_ Ns Sy XXX
249 Print mount information in
256 The file system is to be mounted read-only.
257 Mount the file system read-only (even the super-user may not write it).
263 .It Fl t Ar ufs | external_type
264 The argument following the
266 is used to indicate the file system type.
273 to indicate that the actions should only be taken on
274 filesystems of the specified type.
275 More than one type may be specified in a comma separated list.
276 The list of filesystem types can be prefixed with
278 to specify the filesystem types for which action should
284 .Bd -literal -offset indent
285 mount -a -t nonfs,mfs
288 mounts all filesystems except those of type
293 If the type is not one of the internally known types,
295 will attempt to execute a program in
296 .Pa /sbin/mount_ Ns Sy XXX
299 is replaced by the type name.
300 For example, nfs filesystems are mounted by the program
301 .Pa /sbin/mount_nfs .
303 Most filesystems will be dynamically loaded by their
306 if not already present in the kernel, using the
309 Because this mechanism requires writable temporary space,
310 the filesystem type containing
312 must be compiled into the kernel, and the filesystems containing
318 before any filesystems which might be dynamically loaded.
322 flag indicates that the status of an already mounted file
323 system should be changed.
324 Any of the options discussed above (the
328 also a file system can be changed from read-only to read-write
330 An attempt to change from read-write to read-only will fail if any
331 files on the filesystem are currently open for writing unless the
333 flag is also specified.
334 The set of options is determined by applying the options specified
337 and finally applying the
345 The file system object is to be read and write.
348 Various, most of them are self-explanatory.
350 .Dl XXXXX filesystem is not available
352 The kernel does not support the respective filesystem type.
354 support for a particular filesystem might be provided either on a static
355 (kernel compile-time), or dynamic basis (loaded as a kernel module by
359 or its subprocesses attempt to dynamically load a filesystem module if
360 it has not been configured statically, using
362 In this case, the above error message can also mean that you did not
363 have permission to load the module.
365 .Bl -tag -width /etc/fstab -compact
377 .Xr mount_linprocfs 8 ,
393 It is possible for a corrupted file system to cause a crash.
397 the permissions on the original mount point determine if
399 is accessible from the mounted file system.
400 The minimum permissions for
401 the mount point for traversal across the mount point in both
402 directions to be possible for all users is 0111 (execute for all).