1 .\" Copyright (c) 1980, 1989, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
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.
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
32 .\" @(#)mount.2 8.3 (Berkeley) 5/24/95
42 .Nd mount or dismount a file system
49 .Fn mount "const char *type" "const char *dir" "int flags" "void *data"
51 .Fn unmount "const char *dir" "int flags"
54 .Fn nmount "struct iovec *iov" "u_int niov" "int flags"
59 a file system object onto the system file tree
64 describes the file system object to be mounted.
67 tells the kernel how to interpret
72 The contents of the file system
73 become available through the new mount point
78 of a successful mount are swept under the carpet so to speak, and
79 are unavailable until the file system is unmounted.
83 system call behaves similarly to
85 except that the mount options (file system type name, device to mount,
86 mount-point name, etc.) are passed as an array of name-value pairs
92 The following options are required by all file systems:
93 .Bl -item -offset indent -compact
95 .Li fstype Ta file system type name (e.g., Dq Li procfs )
97 .Li fspath Ta mount point pathname (e.g., Dq Li /proc )
100 Depending on the file system type, other options may be
101 recognized or required;
102 for example, most disk-based file systems require a
104 option containing the pathname of a special device
105 in addition to the options listed above.
107 By default only the super-user may call the
110 This restriction can be removed by setting the
119 suppress default semantics which affect file system access.
120 .Bl -tag -width MNT_SYNCHRONOUS
122 The file system should be treated as read-only;
123 even the super-user may not write on it.
124 Specifying MNT_UPDATE without this option will upgrade
125 a read-only file system to read/write.
127 Do not allow files to be executed from the file system.
129 Do not honor setuid or setgid bits on files when executing them.
130 This flag is set automatically when the caller is not the super-user.
132 Disable update of file access times.
134 Create a snapshot of the file system.
135 This is currently only supported on UFS2 file systems, see
137 for more information.
139 Directories with the SUID bit set chown new files to their own owner.
140 This flag requires the SUIDDIR option to have been compiled into the kernel
146 pages for more information.
147 .It Dv MNT_SYNCHRONOUS
148 All I/O to the file system should be done synchronously.
150 All I/O to the file system should be done asynchronously.
152 Force a read-write mount even if the file system appears to be unclean.
158 specify that the file system is to be forcibly downgraded to a read-only
159 mount even if some files are open for writing.
160 .It Dv MNT_NOCLUSTERR
161 Disable read clustering.
162 .It Dv MNT_NOCLUSTERW
163 Disable write clustering.
168 indicates that the mount command is being applied
169 to an already mounted file system.
170 This allows the mount flags to be changed without requiring
171 that the file system be unmounted and remounted.
172 Some file systems may not allow all flags to be changed.
174 many file systems will not allow a change from read-write to read-only.
178 causes the vfs subsystem to update its data structures pertaining to
179 the specified already mounted file system.
183 argument names the file system.
184 The types of file systems known to the system can be obtained with
190 is a pointer to a structure that contains the type
191 specific arguments to mount.
192 The format for these argument structures is described in the
193 manual page for each file system.
194 By convention file system manual pages are named
195 by prefixing ``mount_'' to the name of the file system as returned by
199 file system is described by the
202 It should be noted that a manual page for default
203 file systems, known as UFS and UFS2, does not exist.
207 system call disassociates the file system from the specified
215 to specify that the file system should be forcibly unmounted
216 even if files are still active.
217 Active special devices continue to work,
218 but any further accesses to any other active files result in errors
219 even if the file system is later remounted.
225 should instead be a file system ID encoded as
226 .Dq Li FSID : Ns Ar val0 : Ns Ar val1 ,
231 are the contents of the
235 The file system that has the specified file system ID will be unmounted.
243 system calls will fail when one of the following occurs:
246 The caller is neither the super-user nor the owner of
248 .It Bq Er ENAMETOOLONG
249 A component of a pathname exceeded 255 characters,
250 or the entire length of a path name exceeded 1023 characters.
252 Too many symbolic links were encountered in translating a pathname.
265 Another process currently holds a reference to
271 points outside the process's allocated address space.
274 The following errors can occur for a
279 A component of ufs_args
286 is not a block device.
288 The major device number of
290 is out of range (this indicates no device driver exists
291 for the associated hardware).
296 No space remains in the mount table.
298 The super block for the file system had a bad magic
299 number or an out of range block size.
301 Not enough memory was available to read the cylinder
302 group information for the file system.
304 An I/O error occurred while reading the super block or
305 cylinder group information.
310 points outside the process's allocated address space.
313 The following errors can occur for a
319 timed out trying to contact the server.
321 Some part of the information described by nfs_args
322 points outside the process's allocated address space.
327 system call may fail with one of the following errors:
330 The caller is neither the super-user nor the user who issued the corresponding
333 .It Bq Er ENAMETOOLONG
334 The length of the path name exceeded 1023 characters.
336 The requested directory is not in the mount table.
338 The file system ID specified using
340 was not found in the mount table.
342 The file system ID specified using
344 could not be decoded.
346 The specified file system is the root file system.
348 A process is holding a reference to a file located
351 An I/O error occurred while writing cached file system information.
356 points outside the process's allocated address space.
361 mount can also fail if the maximum number of file systems are currently
373 functions appeared in
376 Some of the error codes need translation to more obvious messages.