.\" $OpenBSD: mount.2,v 1.18 2000/04/15 11:46:03 aaron Exp $ .\" $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 .Sh NAME .Nm mount , .Nm unmount .Nd mount or dismount a filesystem .Sh SYNOPSIS .Fd #include .Fd #include .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 .Fa dir . The argument .Fa data describes the filesystem object to be mounted. The argument .Fa type tells the kernel how to interpret .Fa data (see .Fa type below). The contents of the filesystem become available through the new mount point .Fa dir . Any files in .Fa dir at the time of a successful mount are swept under the carpet, so to speak, and are unavailable until the filesystem is unmounted. .Pp The following .Fa flags may be specified to suppress default semantics which affect filesystem access. .Bl -tag -width MNT_SYNCHRONOUS .It Dv MNT_RDONLY The filesystem should be treated as read-only: even the superuser may not write to it. .It Dv MNT_NOATIME Do not update the access time on files in the filesystem unless the modification or status change times are also being updated. .It Dv MNT_NOEXEC Do not allow files to be executed from the filesystem. .It Dv MNT_NOSUID Do not honor setuid or setgid bits on files when executing them. .It Dv MNT_NODEV Do not interpret special files on the filesystem. .It Dv MNT_UNION Mount in such a way that the contents of the underlying filesystem are not (totally) obscured (see .Xr mount_union 8 ) . .It Dv MNT_SYNCHRONOUS All I/O to the filesystem should be done synchronously. .El .Pp 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. .Pp The .Fa type argument defines the type of the filesystem. The types of filesystems known to the system are defined in .Aq Pa sys/mount.h . .Fa data is a pointer to a structure that contains the type specific arguments to mount. The currently supported types of filesystems and their type specific data are: .Pp .Dv MOUNT_FFS .Bd -literal -offset indent -compact struct ufs_args { char *fspec; /* block special file to mount */ struct export_args export; /* network export information */ }; .Ed .Pp .Dv MOUNT_NFS .Bd -literal -offset indent -compact struct nfs_args { int version; /* args structure version */ struct sockaddr *addr; /* file server address */ int addrlen; /* length of address */ int sotype; /* Socket type */ int proto; /* and Protocol */ u_char *fh; /* File handle to be mounted */ int fhsize; /* Size, in bytes, of fh */ int flags; /* flags */ int wsize; /* write size in bytes */ int rsize; /* read size in bytes */ int readdirsize; /* readdir size in bytes */ int timeo; /* initial timeout in .1 secs */ int retrans; /* times to retry send */ int maxgrouplist; /* Max. size of group list */ int readahead; /* # of blocks to readahead */ int leaseterm; /* Term (sec) of lease */ int deadthresh; /* Retrans threshold */ char *hostname; /* server's name */ int acregmin; /* Attr cache file recently modified */ int acregmax; /* ac file not recently modified */ int acdirmin; /* ac for dir recently modified */ int acdirmax; /* ac for dir not recently modified */ }; .Ed .Pp .Dv MOUNT_MFS .Bd -literal -offset indent -compact struct mfs_args { char *fspec; /* name to export for statfs */ struct export_args export; /* if we can export an MFS */ caddr_t base; /* base of filesystem in mem */ u_long size; /* size of filesystem */ }; .Ed .Pp The .Fn unmount function call disassociates the filesystem from the specified mount point .Fa dir . .Pp 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 .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. .Pp .Fn unmount returns the value 0 if the unmount was successful; 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: .Bl -tag -width [ENAMETOOLONG] .It Bq Er EPERM The caller is not the superuser. .It Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv {NAME_MAX} characters, or an entire path name exceeded .Dv {PATH_MAX} characters. .It Bq Er ELOOP Too many symbolic links were encountered in translating a pathname. .It Bq Er ENOENT A component of .Fa dir does not exist. .It Bq Er ENOTDIR A component of .Ar name is not a directory, or a path prefix of .Ar special is not a directory. .It Bq Er EINVAL A pathname contains a character with the high-order bit set. .It Bq Er EBUSY Another process currently holds a reference to .Fa dir . .It Bq Er EFAULT .Fa dir points outside the process's allocated address space. .It Bq Er EOPNOTSUPP .Fa type is not supported by the kernel. .El .Pp The following errors can occur for a .Dq ufs filesystem mount: .Bl -tag -width [ENOTBLK] .It Bq Er ENODEV A component of ufs_args .Fa fspec does not exist. .It Bq Er ENOTBLK .Fa fspec is not a block device. .It Bq Er ENXIO The major device number of .Fa fspec is out of range (this indicates no device driver exists for the associated hardware). .It Bq Er EBUSY .Fa fspec is already mounted. .It Bq Er EMFILE No space remains in the mount table. .It Bq Er EINVAL The super block for the filesystem had a bad magic number or an out of range block size. .It Bq Er ENOMEM Not enough memory was available to read the cylinder group information for the filesystem. .It Bq Er EIO An I/O error occurred while reading the super block or cylinder group information. .It Bq Er EFAULT .Fa fspec points outside the process's allocated address space. .El .Pp The following errors can occur for a .Em nfs filesystem mount: .Bl -tag -width [ETIMEDOUT] .It Bq Er ETIMEDOUT .Em Nfs timed out trying to contact the server. .It Bq Er EFAULT Some part of the information described by nfs_args points outside the process's allocated address space. .El .Pp The following errors can occur for a .Em mfs filesystem mount: .Bl -tag -width [EMFILE] .It Bq Er EMFILE No space remains in the mount table. .It Bq Er EINVAL The super block for the filesystem had a bad magic number or an out of range block size. .It Bq Er ENOMEM Not enough memory was available to read the cylinder group information for the filesystem. .It Bq Er EIO A paging error occurred while reading the super block or cylinder group information. .It Bq Er EFAULT .Em Name points outside the process's allocated address space. .El .Pp .Fn unmount may fail with one of the following errors: .Bl -tag -width [ENAMETOOLONG] .It Bq Er EPERM The caller is not the superuser. .It Bq Er ENOTDIR A component of the path is not a directory. .It Bq Er EINVAL The pathname contains a character with the high-order bit set. .It Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv {NAME_MAX} characters, or an entire path name exceeded .Dv {PATH_MAX} characters. .It Bq Er ELOOP Too many symbolic links were encountered in translating the pathname. .It Bq Er EINVAL The requested directory is not in the mount table. .It Bq Er EBUSY A process is holding a reference to a file located on the filesystem. .It Bq Er EIO An I/O error occurred while writing cached filesystem information. .It Bq Er EFAULT .Fa dir points outside the process's allocated address space. .El .Pp A .Dq ufs or .Dq mfs mount can also fail if the maximum number of filesystems are currently mounted. .Sh SEE ALSO .Xr statfs 2 , .Xr mfs 8 , .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 unmount function calls appeared in .At v6 .