2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
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.\" $NetBSD: mount.2,v 1.45 2010/05/31 12:16:20 njoly Exp $
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.\"
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.\" 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. 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 April 10, 2009
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.Dt MOUNT 2
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.Os
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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 file system
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/param.h
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.In 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" "size_t data_len"
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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 file system 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 file system object to be mounted, and is
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.Ar data_len
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bytes long.
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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 file system
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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 file system 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 file system access.
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.Bl -tag -width MNT_SYNCHRONOUS
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.It Dv MNT_RDONLY
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The file system should be treated as read-only;
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even the super-user may not write on it.
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.It Dv MNT_UNION
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Union with underlying filesystem instead of obscuring it.
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.It Dv MNT_HIDDEN
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Cause the
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.Xr df 1
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program, and perhaps others, to, by default,
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exclude this filesystem from its output.
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.It Dv MNT_NOEXEC
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Do not allow files to be executed from the file system.
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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_NODEV
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Do not interpret special files on the file system.
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.It Dv MNT_NOCOREDUMP
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Do not allow programs to dump core files on the file system.
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.It Dv MNT_NOATIME
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Never update access time in the file system.
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.It Dv MNT_NODEVMTIME
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Never update modification time of device files.
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.It Dv MNT_SYMPERM
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Recognize the permission of symbolic link when reading or traversing.
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.It Dv MNT_SYNCHRONOUS
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All I/O to the file system should be done synchronously.
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This will slow I/O performance considerably, but
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enhances overall filesystem reliability.
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.It Dv MNT_ASYNC
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All I/O to the file system should be done asynchronously.
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This vastly improves I/O throughput,
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but at a cost of making the filesystem likely to be
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completely unrecoverable should the system crash while
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unwritten data is pending in kernel buffers.
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.It Dv MNT_LOG
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Use a filesystem journal.
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.Dv MNT_LOG
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causes a journal (or log) to be created in the
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filesystem, creating a record of meta-data writes to be
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performed, allowing the actual writes to be deferred.
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This improves performance in most cases.
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.El
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.Pp
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The
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.Dv MNT_UPDATE ,
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.Dv MNT_RELOAD ,
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and
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.Dv MNT_GETARGS
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flags indicate that the mount command is being applied
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to an already mounted file system.
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The
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.Dv MNT_UPDATE
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flag allows the mount flags to be changed without requiring
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that the file system be unmounted and remounted.
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A conversion from read-write to read-only will fail if any files
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are currently open for writing on the filesystem, unless the
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.Dv MNT_FORCE
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flag is also applied.
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Some file systems may not allow all flags to be changed.
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For example,
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some file systems will not allow a change from read-write to read-only.
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The
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.Dv MNT_RELOAD
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flag causes kernel filesystem data to be reloaded from
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the filesystem device.
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It is only permitted on filesystems mounted read-only.
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Its purpose is to notify the system that the filesystem
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data has been modified by some external process.
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The
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.Dv MNT_GETARGS
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flag does not alter any of the mounted filesystem's properties,
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but returns the filesystem-specific arguments for the currently mounted
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filesystem.
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.Pp
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The
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.Fa type
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argument defines the type of the file system.
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The types of file systems known to the system are defined in
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.In sys/mount.h ,
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and those supported by the current running kernel obtained
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using
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.Xr sysctl 8
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to obtain the node
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.\" .Bd -literal -offset indent
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vfs.generic.fstypes.
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.\" XXX from lite-2:
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.\" The types of filesystems known to the system can be obtained with
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.\" .Xr sysctl 8
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.\" by using the command:
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.\" .Bd -literal -offset indent
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.\" sysctl vfs
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.\" .Ed
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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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Some of the currently supported types of file systems and
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their type specific data are:
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.Pp
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.Dv MOUNT_FFS
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.Bd -literal -offset indent -compact
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struct ufs_args {
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char *fspec; /* block special file to mount */
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};
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.Ed
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.Pp
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.Dv MOUNT_NFS
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.Bd -literal -offset indent -compact
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struct nfs_args {
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int version; /* args structure version */
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struct sockaddr *addr; /* file server address */
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int addrlen; /* length of address */
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int sotype; /* Socket type */
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int proto; /* and Protocol */
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u_char *fh; /* File handle to be mounted */
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int fhsize; /* Size, in bytes, of fh */
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int flags; /* flags */
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int wsize; /* write size in bytes */
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int rsize; /* read size in bytes */
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int readdirsize; /* readdir size in bytes */
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int timeo; /* initial timeout in .1 secs */
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int retrans; /* times to retry send */
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int maxgrouplist; /* Max. size of group list */
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int readahead; /* # of blocks to readahead */
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int leaseterm; /* Term (sec) of lease */
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int deadthresh; /* Retrans threshold */
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char *hostname; /* server's name */
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};
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.Ed
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.Pp
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.Dv MOUNT_MFS
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.Bd -literal -offset indent -compact
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struct mfs_args {
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char *fspec; /* name to export for statfs */
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struct export_args30 pad; /* unused */
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caddr_t base; /* base of file system in mem */
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u_long size; /* size of file system */
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};
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.Ed
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.\" XXX from lite-2:
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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 sysctl 8 .
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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 unmount
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function call disassociates the file system 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 file system should be forcibly unmounted even if files are
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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 file system is later remounted.
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.Sh RETURN VALUES
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.Fn mount
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returns the value 0 if the mount was successful,
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the number of bytes written to
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.Ar data
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for
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.Dv MNT_GETARGS ,
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otherwise \-1 is returned 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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.Fn unmount
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returns the value 0 if the unmount 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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.Fn mount
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will fail when one of the following occurs:
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.Bl -tag -width Er
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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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or for an update from read-write to read-only
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there are files on the filesystem open for writes.
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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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.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 ENAMETOOLONG
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A component of a pathname exceeded
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.Brq Dv NAME_MAX
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characters, or an entire path name exceeded
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.Brq Dv PATH_MAX
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characters.
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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 EPERM
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The caller is not the super-user,
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and ordinary user mounts are not permitted or
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this particular request violates the rules.
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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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file system mount:
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.Bl -tag -width Er
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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 EFAULT
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.Ar Fspec
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points outside the process's allocated address space.
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.It Bq Er EINVAL
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The super block for the file system had a bad magic
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number or an out of range block size.
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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 EMFILE
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No space remains in the mount table.
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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 ENOMEM
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Not enough memory was available to read the cylinder
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group information for the file system.
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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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.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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file system mount:
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.Bl -tag -width Er
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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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.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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.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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file system mount:
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.Bl -tag -width Er
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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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.It Bq Er EINVAL
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The super block for the file system had a bad magic
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number or an out of range block size.
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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 EMFILE
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No space remains in the mount table.
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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 file system.
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.El
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.Pp
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.Fn unmount
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may fail with one of the following errors:
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.Bl -tag -width Er
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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 file system.
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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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.It Bq Er EINVAL
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The requested directory is not in the mount table.
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.It Bq Er EIO
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An I/O error occurred while writing cached file system information.
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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 ENAMETOOLONG
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A component of a pathname exceeded
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.Brq Dv NAME_MAX
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characters, or an entire path name exceeded
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.Brq Dv PATH_MAX
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characters.
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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 EPERM
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The caller is not the super-user.
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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 file systems are currently
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mounted.
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.Sh SEE ALSO
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.Xr df 1 ,
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.Xr getvfsstat 2 ,
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.Xr nfssvc 2 ,
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.Xr getmntinfo 3 ,
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.Xr symlink 7 ,
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.Xr mount 8 ,
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.Xr sysctl 8 ,
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.Xr umount 8
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.Sh HISTORY
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The
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.Fn mount
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and
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.Fn umount
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(now
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.Fn unmount )
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function calls were all present in
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.At v6 .
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.Pp
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Prior to
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.Nx 4.0
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the
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.Nm
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call was used to export NFS filesystems.
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This is now done through
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.Fn nfssvc .
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.Pp
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The
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.Dv data_len
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argument was added for
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.Nx 5.0 .
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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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.Pp
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Far more filesystems are supported than those those listed.
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