$NetBSD: mount.2,v 1.12 1996/02/29 23:47:48 jtc Exp $
Copyright (c) 1980, 1989, 1993
The Regents of the University of California. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
must display the following acknowledgement:
This product includes software developed by the University of
California, Berkeley and its contributors.
4. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
@(#)mount.2 8.2 (Berkeley) 12/11/93
.Dd December 11, 1993 .Dt MOUNT 2 .Os BSD 4 .Sh NAME .Nm mount , .Nm unmount .Nd mount or dismount a filesystem .Sh SYNOPSIS .Fd #include <sys/param.h> .Fd #include <sys/mount.h> .Ft int .Fn mount "const char *type" "const char *dir" "int flags" "void *data" .Ft int .Fn unmount "const char *dir" "int flags" .Sh DESCRIPTION The .Fn mount function grafts a filesystem object onto the system file tree at the point .Ar dir . The argument .Ar data describes the filesystem object to be mounted. The argument .Ar type tells the kernel how to interpret .Ar data (See .Ar type below). The contents of the filesystem become available through the new mount point .Ar dir . Any files in .Ar dir at the time of a successful mount are swept under the carpet so to speak, and are unavailable until the filesystem is unmounted.
p The following .Ar flags may be specified to suppress default semantics which affect filesystem access. l -tag -width MNT_SYNCHRONOUS t Dv MNT_RDONLY The filesystem should be treated as read-only; Even the super-user may not write on it. t Dv MNT_NOEXEC Do not allow files to be executed from the filesystem. t Dv MNT_NOSUID Do not honor setuid or setgid bits on files when executing them. t Dv MNT_NODEV Do not interpret special files on the filesystem. t Dv MNT_UNION Union with underlying filesystem instead of obscuring it. t Dv MNT_SYNCHRONOUS All I/O to the filesystem should be done synchronously. .El
p The flag .Dv MNT_UPDATE indicates that the mount command is being applied to an already mounted filesystem. This allows the mount flags to be changed without requiring that the filesystem be unmounted and remounted. Some filesystems may not allow all flags to be changed. For example, most filesystems will not allow a change from read-write to read-only.
p The flag .Dv MNT_RELOAD causes the vfs subsystem to update its data structures pertaining to the specified already mounted filesystem.
p The .Fa type argument defines the type of the filesystem.
p .Fa Data is a pointer to a structure that contains the type specific arguments to mount. The format for these argument structures is described in the manual page for each filesystem.
p The .Fn umount function call disassociates the filesystem from the specified mount point .Fa dir .
p The .Fa flags argument may specify .Dv MNT_FORCE to specify that the filesystem should be forcibly unmounted even if files are still active. Active special devices continue to work, but any further accesses to any other active files result in errors even if the filesystem is later remounted. .Sh RETURN VALUES The .Fn mount returns the value 0 if the mount was successful, otherwise -1 is returned and the variable .Va errno is set to indicate the error.
p .Nm Umount returns the value 0 if the umount succeeded; otherwise -1 is returned and the variable .Va errno is set to indicate the error. .Sh ERRORS .Fn Mount will fail when one of the following occurs: l -tag -width [ENAMETOOLONG] t Bq Er EPERM The caller is not the super-user, and the device-node and the mountpoint do not have adequate ownership and permissions. t Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv {NAME_MAX} characters, or an entire path name exceeded .Dv {PATH_MAX} characters. t Bq Er ELOOP Too many symbolic links were encountered in translating a pathname. t Bq Er ENOENT A component of .Fa dir does not exist. t Bq Er ENOTDIR A component of .Ar name is not a directory, or a path prefix of .Ar special is not a directory. t Bq Er EINVAL A pathname contains a character with the high-order bit set. t Bq Er EBUSY Another process currently holds a reference to .Fa dir . t Bq Er EFAULT .Fa Dir points outside the process's allocated address space. .El
p .Nm Umount may fail with one of the following errors: l -tag -width [ENAMETOOLONG] t Bq Er EPERM The caller is not the super-user, and the .Nm mount() was not done by the user. t Bq Er ENOTDIR A component of the path is not a directory. t Bq Er EINVAL The pathname contains a character with the high-order bit set. t Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv {NAME_MAX} characters, or an entire path name exceeded .Dv {PATH_MAX} characters. t Bq Er ELOOP Too many symbolic links were encountered in translating the pathname. t Bq Er EINVAL The requested directory is not in the mount table. t Bq Er EBUSY A process is holding a reference to a file located on the filesystem. t Bq Er EIO An I/O error occurred while writing cached filesystem information. t Bq Er EFAULT .Fa Dir points outside the process's allocated address space. .El .Sh SEE ALSO .Xr mount 8 , .Xr umount 8 .Sh BUGS Some of the error codes need translation to more obvious messages. .Sh HISTORY .Fn Mount and .Fn umount function calls appeared in .At v6 .