.\" $NetBSD: mount.2,v 1.8 1995/02/27 12:34:49 cgd 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 file system .Sh SYNOPSIS .Fd #include .Fd #include .Ft int .Fn mount "int type" "const char *dir" "int flags" "caddr_t data" .Ft int .Fn unmount "const char *dir" "int flags" .Sh DESCRIPTION The .Fn mount function grafts a file system object onto the system file tree at the point .Ar dir . The argument .Ar data describes the file system object to be mounted. The argument .Ar type tells the kernel how to interpret .Ar data (See .Ar type below). The contents of the file system 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 file system is unmounted. .Pp The following .Ar flags may be specified to suppress default semantics which affect file system access. .Bl -tag -width MNT_SYNCHRONOUS .It Dv MNT_RDONLY The file system should be treated as read-only; Even the super-user may not write on it. .It Dv MNT_NOEXEC Do not allow files to be executed from the file system. .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 file system. .It Dv MNT_SYNCHRONOUS All I/O to the file system should be done synchronously. .El .Pp The flag .Dv MNT_UPDATE indicates that the mount command is being applied to an already mounted file system. This allows the mount flags to be changed without requiring that the file system be unmounted and remounted. Some file systems may not allow all flags to be changed. For example, most file systems will not allow a change from read-write to read-only. .Pp The .Fa type argument defines the type of the file system. The types of file systems 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 file systems and their type specific data are: .Pp .Dv MOUNT_UFS .Bd -literal -offset indent -compact struct ufs_args { char *fspec; /* Block special file to mount */ int exflags; /* export related flags */ uid_t exroot; /* mapping for root uid */ }; .Ed .Pp .Dv MOUNT_NFS .Bd -literal -offset indent -compact struct nfs_args { struct sockaddr_in *addr; /* file server address */ nfsv2fh_t *fh; /* File handle to be mounted */ int flags; /* flags */ int wsize; /* write size in bytes */ int rsize; /* read size in bytes */ int timeo; /* initial timeout 0.1 secs */ int retrans; /* times to retry send */ char *hostname; /* server's name */ }; .Ed .Pp .Dv MOUNT_MFS .Bd -literal -offset indent -compact struct mfs_args { char *name; /* name of backing process */ caddr_t base; /* base address of the file system */ u_long size; /* size of the file system */ }; .Ed .Pp The .Fn umount function call disassociates the file system from the specified mount point .Fa dir . .Pp The .Fa flags argument may specify .Dv MNT_FORCE to specify that the file system 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 file system 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. .Pp .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: .Bl -tag -width Er .It Bq Er EPERM The caller is not the super-user. .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 EBUSY Another process currently holds a reference to .Fa dir . .It Bq Er EFAULT .Fa Dir points outside the process's allocated address space. .El .Pp The following errors can occur for a .Em ufs file system mount: .Bl -tag -width Er .It Bq Er ENODEV A component of ufs_args .Ar fspec does not exist. .It Bq Er ENOTBLK .Ar Fspec is not a block device. .It Bq Er ENXIO The major device number of .Ar fspec is out of range (this indicates no device driver exists for the associated hardware). .It Bq Er EBUSY .Ar Fspec is already mounted. .It Bq Er EMFILE No space remains in the mount table. .It Bq Er EINVAL The super block for the file system 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 file system. .It Bq Er EIO An I/O error occurred while reading the super block or cylinder group information. .It Bq Er EFAULT .Ar Fspec points outside the process's allocated address space. .El .Pp The following errors can occur for a .Em nfs file system mount: .Bl -tag -width Er .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 file system mount: .Bl -tag -width Er .It Bq Er EMFILE No space remains in the mount table. .It Bq Er EINVAL The super block for the file system 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 file system. .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 .Nm Umount may fail with one of the following errors: .Bl -tag -width Er .It Bq Er EPERM The caller is not the super-user. .It Bq Er ENOTDIR A component of the path is not a directory. .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 file system. .It Bq Er EIO An I/O error occurred while writing cached file system information. .It Bq Er EFAULT .Fa Dir points outside the process's allocated address space. .El .Pp A .Em ufs or .Em mfs mount can also fail if the maximum number of file systems are currently mounted. .Sh SEE ALSO .Xr mount 8 , .Xr umount 8 , .Xr mfs 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 .