588 lines
16 KiB
Groff
588 lines
16 KiB
Groff
.\" $NetBSD: mount.8,v 1.87 2018/01/09 09:15:57 wiz Exp $
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.\"
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.\" Copyright (c) 1980, 1989, 1991, 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.8 8.8 (Berkeley) 6/16/94
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.\"
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.Dd January 8, 2018
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.Dt MOUNT 8
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.Os
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.Sh NAME
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.Nm mount
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.Nd mount file systems
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.Sh SYNOPSIS
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.Nm
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.Op Fl Aadfruvw
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.Op Fl t Ar type
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.Nm
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.Op Fl dfruvw
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.Brq Ar special | Ar node
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.Nm
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.Op Fl dfruvw
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.Op Fl o Ar options
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.Op Fl t Ar type
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.Ar special node
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.Sh DESCRIPTION
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The
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.Nm
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command invokes a file system-specific program to prepare and graft the
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.Ar special
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device on to the file system tree at the point
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.Ar node ,
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or to update options for an already-mounted file system.
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.Pp
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These programs are named
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.Dq mount_<fstype>
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where
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.Dq <fstype>
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refers to the file system-specific type; for example
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for NFS the mount program is called
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.Xr mount_nfs 8 .
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.Pp
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The
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.Ar node
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argument is always interpreted as a directory in the name space of
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currently mounted file systems.
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The
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.Ar special
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argument is interpreted in different ways
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by the programs that handle different file system types;
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for example,
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.Xr mount_ffs 8
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interprets it as a device node,
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.Xr mount_null 8
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interprets it as a directory name,
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.Xr mount_nfs 8
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interprets it as reference to a remote host and a directory on that host,
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and
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.Xr mount_tmpfs 8
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ignores it.
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.Pp
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The system maintains a list of currently mounted file systems.
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This list is printed if
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.Nm
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is invoked with no arguments, and with no options that require some
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other behaviour.
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.Pp
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If exactly one of
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.Ar special
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or
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.Ar node
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is provided, then the missing information
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(including the file system type)
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is taken from the
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.Xr fstab 5
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file.
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The provided argument is looked up first in the
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.Dq fs_file ,
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then in the
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.Dq fs_spec
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column.
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If the matching entry in
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.Xr fstab 5
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has the string
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.Dq Li from_mount
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as its
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.Dq fs_spec
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field, the device or remote file system already mounted at
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the location specified by
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.Dq fs_spec
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will be used.
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.\" XXX The above paragraph doesn't address the use of "-u"
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.Pp
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If both
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.Ar special
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and
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.Ar node
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are provided, then
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.Xr fstab 5
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is not used.
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In this case, if the file system type is not specified
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via the
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.Fl t
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flag, then
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.Nm
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may determine the type from the disk label (see
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.Xr disklabel 8 ) .
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In addition, if
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.Ar special
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contains a colon
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.Pq Ql \&:
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or at sign
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.Pq Ql \&@ ,
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then the
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.Li nfs
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type is inferred, but this behaviour is deprecated, and will be
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removed in a future version of
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.Nm .
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.Pp
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In
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.Nx ,
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the file-system mounting policy is dictated by the running security models.
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The default security model may allow unprivileged mounting; see
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.Xr secmodel_suser 9
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and
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.Xr secmodel_extensions 9
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for details.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl A
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Causes
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.Nm
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to try to mount all of the file systems listed in the
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.Xr fstab 5
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file except those for which the
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.Dq noauto
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option is specified.
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.It Fl a
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Similar to the
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.Fl A
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flag, except that if a file system (other than the root file system)
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appears to be already mounted,
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.Nm
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will not try to mount it again.
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.Nm
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assumes that a file system is already mounted if a file system with
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the same type is mounted on the given mount point.
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More stringent checks are not possible because some file system types
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report strange values for the mounted-from device for mounted file
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systems.
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.It Fl d
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Causes everything to be done except for the invocation of
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the file system-specific program.
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This option is useful in conjunction with the
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.Fl v
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flag to determine what the
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.Nm
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command is trying to do.
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.It Fl f
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Forces the revocation of write access when trying to downgrade
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a file system mount status from read-write to read-only.
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.It Fl o
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Options are specified with a
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.Fl o
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flag followed by a comma separated string of options.
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The following options are available:
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.Bl -tag -width nocoredump
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.It Cm async
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All I/O to the file system should be done asynchronously.
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In the event of a crash,
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.Em "it is impossible for the system to verify the integrity of data on a file system mounted with this option" .
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You should only use this option if you have an application-specific data
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recovery mechanism, or are willing to recreate the file system from scratch.
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.It Cm noasync
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Clear
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.Cm async
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mode.
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.It Cm automounted
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This flag indicates that the file system was mounted by
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.Xr automountd 8 .
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Automounted file systems are automatically unmounted by
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.Xr autounmountd 8 .
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.It Cm discard
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Use DISCARD/TRIM commands if disk and driver support it.
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.Pp
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.Em EXPERIMENTAL
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- negatively influences filesystem performance by increasing fragmentation,
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causes free block map inconsistency on unclean shutdown,
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and is incompatible with
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.Cm log .
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If
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.Cm log
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option is also used,
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.Cm discard
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is automatically disabled.
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.It Cm extattr
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Enable extended attributes, if the filesystem supports them and
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does not enable them by default.
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Currently this is only the case for UFS1.
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.It Cm force
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The same as
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.Fl f ;
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forces the revocation of write access when trying to downgrade
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a file system mount status from read-write to read-only.
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.It Cm getargs
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Retrieves the file system specific mount arguments for the given
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mounted file system and prints them.
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.It Cm hidden
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By setting the
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.Dv MNT_IGNORE
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flag,
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causes the mount point to be excluded from the
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list of file systems shown by default with
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.Xr df 1 .
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.It Cm noatime
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Never update the access time field for files.
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This option is useful for optimizing read performance on file systems
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that are used as news spools.
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.It Cm noauto
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This file system should be skipped when mount is run with the
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.Fl a
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flag.
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.It Cm nocoredump
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Do not allow programs to create crash dumps (core files) on the file system.
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This option can be used to help protect sensitive
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data by keeping core files (which may contain sensitive data)
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from being created on insecure file systems.
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Only core files that would be created by program crashes are
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prevented by use of this flag; the behavior of
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.Xr savecore 8
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is not affected.
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.It Cm nodev
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Do not interpret character or block special devices on the file system.
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This option is useful for a server that has file systems containing
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special devices for architectures other than its own.
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.It Cm nodevmtime
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Do not update modification times on device special files.
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This option is useful on laptops
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or other systems that perform power management.
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.It Cm noexec
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Do not allow execution of any binaries on the mounted file system.
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This option is useful for a server that has file systems containing
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binaries for architectures other than its own.
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.It Cm nosuid
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Do not allow set-user-identifier or set-group-identifier bits to take effect.
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.It Cm port
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(NFS only) Use the specified NFS port.
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.It Cm rdonly
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The same as
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.Fl r ;
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mount the file system read-only (even the super-user may not write it).
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.It Cm reload
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Reload all incore data for a file system.
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This is used mainly after running
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.Xr fsck 8
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on the root file system and finding things to fix.
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The file system must be mounted read-only.
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All cached meta-data are invalidated, superblock and summary information
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is re-read from disk, all cached inactive vnodes and file data are
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invalidated and all inode data are re-read for all active vnodes.
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.It Cm rump
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Instead of running
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.Dq mount_<fstype>
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to mount the file system, run
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.Dq rump_<fstype> .
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This uses a userspace server to mount the file system and does not
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require kernel support for the specific file system type.
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See the
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.Fl t
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flag and respective rump_type manual page for more information.
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.It Cm log
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(FFS only)
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Mount the file system with
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.Xr wapbl 4
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meta-data journaling, also known simply as logging.
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It provides rapid metadata updates and eliminates the need to check
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file system consistency after a system outage.
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It requires the
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.Dv WAPBL
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option to be enabled in the running kernel.
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See
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.Xr wapbl 4
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for more information.
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This option requires the
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.Dq UFS2
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.Pq level 4
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superblock layout, which is the default for newly created FFSv1 and
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FFSv2 file systems.
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To update an old file system with an earlier superblock format,
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use the
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.Fl c
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option of
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.Xr fsck_ffs 8 .
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.Pp
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.Cm log
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cannot be used together with
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.Cm discard .
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.Pp
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A file system mounted with
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.Cm log
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can be mounted also with
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.Cm async ,
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but such filesystem behaves the same as if
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.Cm async
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was not specified - meta-data writes use the log, hence its integrity
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is still guaranteed.
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.It Cm symperm
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Recognize permission of symbolic link when reading or traversing link.
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.It Cm sync
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All I/O to the file system should be done synchronously.
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This is not equivalent to the normal mode in which only
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metadata is written synchronously.
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.It Cm nosync
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Clear
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.Cm sync
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mode.
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.It Cm union
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Causes the namespace at the mount point to appear as the union
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of the mounted file system root
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(referred to as the
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.Em upper
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layer), and the existing directory
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(referred to as the
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.Em lower
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layer).
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Name lookups will be done in the upper layer first.
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If a name does not exist in the upper layer, then the name
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will be looked up in the lower layer.
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If a name exists in both the upper and lower layers, then only
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the upper instance is accessible.
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Creation of new files is done in the upper layer,
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except in the case of the fdesc file system (see
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.Xr mount_fdesc 8 ) .
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.Pp
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Note that the
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.Cm union
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option can be applied to any type of file system,
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and is fundamentally different from
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.Xr mount_union 8 ,
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which is a particular type of file system.
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Also note that the
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.Cm union
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option affects the file system name space only at the mount point
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itself; it does not apply recursively to subdirectories.
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.It Cm update
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The same as
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.Fl u ;
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indicate that the status of an already mounted file system should be changed.
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.El
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.Pp
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Any additional options specific to a given file system type (see the
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.Fl t
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option) may be passed as a comma separated list; these options are
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distinguished by a leading
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.Dq \&-
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(dash).
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Options that take a value are specified using the syntax -option=value.
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For example, the mount command:
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.Bd -literal -offset indent
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mount -t mfs -o nosuid,-N,-s=32m swap /tmp
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.Ed
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.Pp
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causes
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.Nm
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to execute the equivalent of:
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.Bd -literal -offset indent
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/sbin/mount_mfs -o nosuid -N -s 32m swap /tmp
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.Ed
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.It Fl r
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The file system is to be mounted read-only.
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Mount the file system read-only (even the super-user may not write it).
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The same as the
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.Dq rdonly
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argument to the
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.Fl o
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option.
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.It Fl t Ar type
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The argument following the
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.Fl t
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is used to indicate the file system type.
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The type
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.Ar ffs
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is the default.
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The
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.Fl t
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option can be used to indicate that the actions
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should only be taken on file systems of the specified type.
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More than one type may be specified in a comma separated list.
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The list of file system types can be prefixed with
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.Dq no
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to specify the file system types for which action should
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.Em not
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be taken.
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For example, the
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.Nm
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command:
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.Bd -literal -offset indent
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mount -a -t nonfs,mfs
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.Ed
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.Pp
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mounts all file systems except those of type NFS and MFS.
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.Pp
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.Nm
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will attempt to execute a program in
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.Pa /sbin/mount_ Ns Em XXX
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where
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.Em XXX
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is replaced by the type name.
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For example, nfs file systems are mounted by the program
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.Pa /sbin/mount_nfs .
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.It Fl u
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The
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.Fl u
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flag indicates that the status of an already mounted file
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system should be changed.
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Any of the options discussed above (the
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.Fl o
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option)
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may be changed;
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also a file system can be changed from read-only to read-write
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or vice versa.
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An attempt to change from read-write to read-only will fail if any
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files on the file system are currently open for writing unless the
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.Fl f
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flag is also specified.
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The set of options is determined by first extracting the options
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for the file system from the
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.Xr fstab 5
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file, then applying any options specified by the
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.Fl o
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argument,
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and finally applying the
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.Fl r
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or
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.Fl w
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option.
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.It Fl v
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Verbose mode.
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If this flag is specified more than once, then the
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file system-specific mount arguments are printed for the given mounted
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file system.
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.It Fl w
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The file system object is to be read and write.
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.El
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.Pp
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The options specific to the various file system types are
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described in the manual pages for those file systems'
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.Dq mount_<fstype>
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commands;
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for instance, the options specific to Berkeley
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Fast File System (FFS) are described in the
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.Xr mount_ffs 8
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manual page.
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.Pp
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The particular type of file system in each partition of a disk can
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be found by examining the disk label with the
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.Xr disklabel 8
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command.
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.Sh FILES
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.Bl -tag -width /etc/fstab -compact
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.It Pa /etc/fstab
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file system table
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.El
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.Sh EXAMPLES
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|
Some useful examples:
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.Bl -tag -offset indent -width "MS-DOS"
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.It CD-ROM
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mount -t cd9660 -r /dev/cd0a /cdrom
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.It MS-DOS
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mount -t msdos /dev/fd0a /floppy
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.It NFS
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mount -t nfs nfs-server-host:/directory/path /mount-point
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.It MFS (32 megabyte)
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mount -t mfs -o nosuid,-s=32m swap /tmp
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.El
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.Pp
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The
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.Dq noauto
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directive in
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.Pa /etc/fstab
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can be used to make it easy to manually mount and unmount removable
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media using just the mountpoint filename, with an entry like this:
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.Pp
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.Dl /dev/cd0a /cdrom cd9660 ro,noauto 0 0
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.Pp
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That would allow a simple command like
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.Qq mount /cdrom
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or
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.Qq umount /cdrom
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for media using the ISO-9660 file system format in the first
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CD-ROM drive.
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.Sh DIAGNOSTICS
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|
The error
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.Dq Operation not supported by device
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indicates that the mount for the specified file-system type cannot be
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completed because the kernel lacks support for the said file-system.
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See
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.Xr options 4 .
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.Pp
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The error
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.Dq Operation not permitted
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may indicate that the mount options include privileged options and/or
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do not include options that exclude privileged options.
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One should try using at least
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.Dq nodev
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and
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.Dq nosuid
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|
in such cases:
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.Bd -literal -offset indent
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|
mount -t cd9660 -o nodev,nosuid /dev/cd0a /mnt
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.Ed
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.Sh SEE ALSO
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|
.Xr df 1 ,
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.Xr mount 2 ,
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|
.Xr options 4 ,
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.Xr wapbl 4 ,
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|
.Xr fstab 5 ,
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|
.Xr automount 8 ,
|
|
.Xr automountd 8 ,
|
|
.Xr autounmountd 8 ,
|
|
.Xr disklabel 8 ,
|
|
.Xr fsck 8 ,
|
|
.Xr mount_ados 8 ,
|
|
.Xr mount_cd9660 8 ,
|
|
.Xr mount_chfs 8 ,
|
|
.Xr mount_ext2fs 8 ,
|
|
.Xr mount_fdesc 8 ,
|
|
.Xr mount_ffs 8 ,
|
|
.Xr mount_filecore 8 ,
|
|
.Xr mount_kernfs 8 ,
|
|
.Xr mount_lfs 8 ,
|
|
.Xr mount_mfs 8 ,
|
|
.Xr mount_msdos 8 ,
|
|
.Xr mount_nfs 8 ,
|
|
.Xr mount_ntfs 8 ,
|
|
.Xr mount_null 8 ,
|
|
.Xr mount_overlay 8 ,
|
|
.Xr mount_portal 8 ,
|
|
.Xr mount_procfs 8 ,
|
|
.Xr mount_tmpfs 8 ,
|
|
.Xr mount_udf 8 ,
|
|
.Xr mount_umap 8 ,
|
|
.Xr mount_union 8 ,
|
|
.Xr rump_cd9660 8 ,
|
|
.Xr rump_efs 8 ,
|
|
.Xr rump_ext2fs 8 ,
|
|
.Xr rump_ffs 8 ,
|
|
.Xr rump_hfs 8 ,
|
|
.Xr rump_lfs 8 ,
|
|
.Xr rump_msdos 8 ,
|
|
.Xr rump_nfs 8 ,
|
|
.Xr rump_ntfs 8 ,
|
|
.Xr rump_smbfs 8 ,
|
|
.Xr rump_sysvbfs 8 ,
|
|
.Xr rump_tmpfs 8 ,
|
|
.Xr rump_udf 8 ,
|
|
.Xr umount 8
|
|
.Sh HISTORY
|
|
A
|
|
.Nm
|
|
command appeared in
|
|
.At v1 .
|