c931d11d3f
Obtained from: Whistle Communications tree Add an option to the way UFS works dependent on the SUID bit of directories This changes makes things a whole lot simpler on systems running as fileservers for PCs and MACS. to enable the new code you must 1/ enable option SUIDDIR on the kernel. 2/ mount the filesystem with option suiddir. hopefully this makes it difficult enough for people to do this accidentally. see the new chmod(2) man page for detailed info.
326 lines
9.1 KiB
Groff
326 lines
9.1 KiB
Groff
.\" Copyright (c) 1980, 1989, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)mount.2 8.3 (Berkeley) 5/24/95
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.\"
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.Dd May 24, 1995
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.Dt MOUNT 2
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.Os BSD 4
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.Sh NAME
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.Nm mount ,
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.Nm unmount
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.Nd mount or dismount a filesystem
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.Sh SYNOPSIS
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.Fd #include <sys/param.h>
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.Fd #include <sys/mount.h>
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.Ft int
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.Fn mount "const char *type" "const char *dir" "int flags" "void *data"
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.Ft int
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.Fn unmount "const char *dir" "int flags"
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.Sh DESCRIPTION
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The
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.Fn mount
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function grafts
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a filesystem object onto the system file tree
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at the point
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.Ar dir .
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The argument
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.Ar data
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describes the filesystem object to be mounted.
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The argument
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.Ar type
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tells the kernel how to interpret
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.Ar data
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(See
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.Ar type
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below).
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The contents of the filesystem
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become available through the new mount point
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.Ar dir .
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Any files in
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.Ar dir
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at the time
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of a successful mount are swept under the carpet so to speak, and
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are unavailable until the filesystem is unmounted.
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.Pp
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The following
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.Ar flags
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may be specified to
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suppress default semantics which affect filesystem access.
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.Bl -tag -width MNT_SYNCHRONOUS
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.It Dv MNT_RDONLY
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The filesystem should be treated as read-only;
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Even the super-user may not write on it.
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Specifying MNT_UPDATE withut this option will upgrade
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a read-only filesystem to read/write.
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.It Dv MNT_NOEXEC
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Do not allow files to be executed from the filesystem.
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.It Dv MNT_NOSUID
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Do not honor setuid or setgid bits on files when executing them.
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.It Dv MNT_NOATIME
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Disable update of file access times.
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.It Dv MNT_NODEV
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Do not interpret special files on the filesystem.
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.It Dv MNT_SUIDDIR
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Directories with the SUID bit set chown new files to their own owner.
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.It Dv MNT_SYNCHRONOUS
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All I/O to the filesystem should be done synchronously.
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.It Dv MNT_ASYNC
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All I/O to the filesystem should be done asynchronously.
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.It Dv MNT_FORCE
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Fore a read-write mount even if the filesystem appears to be unclean.
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Dangerous.
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.It Dv MNT_NOCLUSTERR
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Disable read clustering.
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.It Dv MNT_NOCLUSTERW
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Disable write clustering.
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.El
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.Pp
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The flag
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.Dv MNT_UPDATE
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indicates that the mount command is being applied
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to an already mounted filesystem.
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This allows the mount flags to be changed without requiring
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that the filesystem be unmounted and remounted.
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Some filesystems may not allow all flags to be changed.
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For example,
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many filesystems will not allow a change from read-write to read-only.
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.Pp
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The flag
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.Dv MNT_RELOAD
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causes the vfs subsystem to update its data structures pertaining to
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the specified already mounted filesystem.
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.Pp
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The
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.Fa type
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argument names the filesystem.
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The types of filesystems known to the system can be obtained with
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.Xr lsvfs 1 .
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.Pp
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.Fa Data
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is a pointer to a structure that contains the type
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specific arguments to mount.
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The format for these argument structures is described in the
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manual page for each filesystem.
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By convention filesystem manual pages are named
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by prefixing ``mount_'' to the name of the filesystem as returned by
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.Xr lsvfs 1 .
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Thus the
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.Nm NFS
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filesystem is described by the
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.Xr mount_nfs 8
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manual page.
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.Pp
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The
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.Fn umount
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function call disassociates the filesystem from the specified
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mount point
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.Fa dir .
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.Pp
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The
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.Fa flags
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argument may specify
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.Dv MNT_FORCE
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to specify that the filesystem should be forcibly unmounted or made read-only
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(if MNT_UPDATE and MNT_RDONLY are also specified)
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even if files are still active.
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Active special devices continue to work,
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but any further accesses to any other active files result in errors
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even if the filesystem is later remounted.
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.Pp
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The
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.Dv MNT_SUIDDIR
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option requires the SUIDDIR option to have been compiled into the kernel
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to have any effect.
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See the
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.Xr mount 8
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and
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.Xr chmod 2
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pages for more information.
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.Sh RETURN VALUES
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The
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.Fn mount
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returns the value 0 if the mount was successful, otherwise -1 is returned
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and the variable
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.Va errno
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is set to indicate the error.
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.Pp
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The
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.Fn umount
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function returns the value 0 if the umount succeeded; otherwise -1 is returned
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and the variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The
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.Fn mount
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function will fail when one of the following occurs:
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.Bl -tag -width [ENOTBLK]
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.It Bq Er EPERM
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The caller is not the super-user.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded 255 characters,
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or the entire length of a path name exceeded 1023 characters.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating a pathname.
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.It Bq Er ENOENT
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A component of
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.Fa dir
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does not exist.
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.It Bq Er ENOTDIR
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A component of
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.Ar name
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is not a directory,
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or a path prefix of
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.Ar special
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is not a directory.
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.It Bq Er EBUSY
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Another process currently holds a reference to
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.Fa dir .
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.It Bq Er EFAULT
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.Fa Dir
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points outside the process's allocated address space.
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.El
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.Pp
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The following errors can occur for a
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.Em ufs
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filesystem mount:
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.Bl -tag -width [ENOTBLK]
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.It Bq Er ENODEV
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A component of ufs_args
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.Ar fspec
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does not exist.
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.It Bq Er ENOTBLK
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.Ar Fspec
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is not a block device.
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.It Bq Er ENXIO
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The major device number of
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.Ar fspec
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is out of range (this indicates no device driver exists
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for the associated hardware).
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.It Bq Er EBUSY
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.Ar Fspec
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is already mounted.
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.It Bq Er EMFILE
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No space remains in the mount table.
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.It Bq Er EINVAL
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The super block for the filesystem had a bad magic
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number or an out of range block size.
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.It Bq Er ENOMEM
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Not enough memory was available to read the cylinder
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group information for the filesystem.
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.It Bq Er EIO
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An I/O error occurred while reading the super block or
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cylinder group information.
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.It Bq Er EFAULT
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.Ar Fspec
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points outside the process's allocated address space.
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.El
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.Pp
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The following errors can occur for a
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.Em nfs
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filesystem mount:
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.Bl -tag -width [ENOTBLK]
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.It Bq Er ETIMEDOUT
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.Em Nfs
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timed out trying to contact the server.
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.It Bq Er EFAULT
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Some part of the information described by nfs_args
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points outside the process's allocated address space.
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.El
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.Pp
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The following errors can occur for a
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.Em mfs
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filesystem mount:
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.Bl -tag -width [ENOTBLK]
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.It Bq Er EMFILE
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No space remains in the mount table.
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.It Bq Er EINVAL
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The super block for the filesystem had a bad magic
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number or an out of range block size.
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.It Bq Er ENOMEM
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Not enough memory was available to read the cylinder
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group information for the filesystem.
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.It Bq Er EIO
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A paging error occurred while reading the super block or
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cylinder group information.
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.It Bq Er EFAULT
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.Em Name
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points outside the process's allocated address space.
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.El
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.Pp
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The
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.Fn umount
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function may fail with one of the following errors:
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.Bl -tag -width [ENOTBLK]
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.It Bq Er EPERM
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The caller is not the super-user.
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.It Bq Er ENOTDIR
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A component of the path is not a directory.
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.It Bq Er EINVAL
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The pathname contains a character with the high-order bit set.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded 255 characters,
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or an entire path name exceeded 1023 characters.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.It Bq Er EINVAL
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The requested directory is not in the mount table.
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.It Bq Er EBUSY
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A process is holding a reference to a file located
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on the filesystem.
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.It Bq Er EIO
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An I/O error occurred while writing cached filesystem information.
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.It Bq Er EFAULT
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.Fa Dir
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points outside the process's allocated address space.
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.El
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.Pp
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A
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.Em ufs
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or
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.Em mfs
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mount can also fail if the maximum number of filesystems are currently
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mounted.
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.Sh SEE ALSO
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.Xr lsvfs 1 ,
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.Xr mfs 8 ,
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.Xr mount 8 ,
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.Xr umount 8
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.Sh BUGS
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Some of the error codes need translation to more obvious messages.
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.Sh HISTORY
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.Fn Mount
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and
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.Fn umount
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function calls appeared in
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.At v6 .
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