399 lines
10 KiB
Groff
399 lines
10 KiB
Groff
.\" 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. 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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.\" @(#)fstab.5 8.1 (Berkeley) 6/5/93
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.\" $FreeBSD$
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.\"
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.Dd July 15, 2013
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.Dt FSTAB 5
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.Os
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.Sh NAME
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.Nm fstab
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.Nd static information about the file systems
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.Sh SYNOPSIS
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.In fstab.h
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.Sh DESCRIPTION
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The file
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.Nm
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contains descriptive information about the various file
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systems.
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.Nm
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is only read by programs, and not written;
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it is the duty of the system administrator to properly create
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and maintain this file.
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Each file system is described on a separate line;
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fields on each line are separated by tabs or spaces.
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The order of records in
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.Nm
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is important because
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.Xr fsck 8 ,
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.Xr mount 8 ,
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and
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.Xr umount 8
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sequentially iterate through
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.Nm
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doing their thing.
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.Pp
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The first field,
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.Pq Fa fs_spec ,
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describes the special device or
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remote file system to be mounted.
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The contents are decoded by the
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.Xr strunvis 3
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function.
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This allows using spaces or tabs in the device name which would be
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interpreted as field separators otherwise.
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.Pp
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The second field,
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.Pq Fa fs_file ,
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describes the mount point for the file system.
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For swap partitions, this field should be specified as
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.Dq none .
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The contents are decoded by the
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.Xr strunvis 3
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function, as above.
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.Pp
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The third field,
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.Pq Fa fs_vfstype ,
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describes the type of the file system.
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The system can support various file system types.
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Only the root, /usr, and /tmp file systems need be statically
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compiled into the kernel;
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everything else will be automatically loaded at mount
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time.
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(Exception: the FFS cannot currently be demand-loaded.)
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Some people still prefer to statically
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compile other file systems as well.
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.Pp
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The fourth field,
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.Pq Fa fs_mntops ,
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describes the mount options associated with the file system.
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It is formatted as a comma separated list of options.
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It contains at least the type of mount (see
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.Fa fs_type
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below) plus any additional options appropriate to the file system type.
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See the options flag
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.Pq Fl o
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in the
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.Xr mount 8
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page and the file system specific page, such as
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.Xr mount_nfs 8 ,
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for additional options that may be specified.
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All options that can be given to the file system specific mount commands
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can be used in
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.Nm
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as well.
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They just need to be formatted a bit differently.
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The arguments of the
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.Fl o
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option can be used without the preceding
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.Fl o
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flag.
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Other options need both the file system specific flag and its argument,
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separated by an equal sign.
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For example, mounting an
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.Xr msdosfs 5
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filesystem, the options
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.Bd -literal -offset indent
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-o sync -o noatime -m 644 -M 755 -u foo -g bar
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.Ed
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.Pp
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should be written as
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.Bd -literal -offset indent
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sync,noatime,-m=644,-M=755,-u=foo,-g=bar
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.Ed
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.Pp
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in the option field of
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.Nm .
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.Pp
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If the options
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.Dq userquota
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and/or
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.Dq groupquota
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are specified,
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the file system is automatically processed by the
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.Xr quotacheck 8
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command, and user and/or group disk quotas are enabled with
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.Xr quotaon 8 .
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By default,
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file system quotas are maintained in files named
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.Pa quota.user
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and
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.Pa quota.group
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which are located at the root of the associated file system.
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These defaults may be overridden by putting an equal sign
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and an alternative absolute pathname following the quota option.
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Thus, if the user quota file for
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.Pa /tmp
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is stored in
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.Pa /var/quotas/tmp.user ,
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this location can be specified as:
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.Bd -literal -offset indent
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userquota=/var/quotas/tmp.user
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.Ed
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.Pp
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If the option
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.Dq failok
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is specified,
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the system will ignore any error which happens during the mount of that filesystem,
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which would otherwise cause the system to drop into single user mode.
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This option is implemented by the
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.Xr mount 8
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command and will not be passed to the kernel.
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.Pp
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If the option
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.Dq noauto
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is specified, the file system will not be automatically
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mounted at system startup.
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Note that, for network file systems
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of third party types
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(i.e., types supported by additional software
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not included in the base system)
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to be automatically mounted at system startup,
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the
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.Va extra_netfs_types
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.Xr rc.conf 5
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variable must be used to extend the
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.Xr rc 8
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startup script's list of network file system types.
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.Pp
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If the option
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.Dq late
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is specified, the file system will be automatically mounted
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at a stage of system startup after remote mount points are mounted.
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For more detail about this option,
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see the
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.Xr mount 8
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manual page.
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.Pp
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The type of the mount is extracted from the
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.Fa fs_mntops
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field and stored separately in the
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.Fa fs_type
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field (it is not deleted from the
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.Fa fs_mntops
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field).
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If
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.Fa fs_type
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is
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.Dq rw
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or
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.Dq ro
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then the file system whose name is given in the
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.Fa fs_file
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field is normally mounted read-write or read-only on the
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specified special file.
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.Pp
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If
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.Fa fs_type
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is
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.Dq sw
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then the special file is made available as a piece of swap
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space by the
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.Xr swapon 8
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command at the end of the system reboot procedure.
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For vnode-backed swap spaces,
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.Dq file
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is supported in the
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.Fa fs_mntops
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field.
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When
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.Fa fs_spec
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is an
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.Xr md 4
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device file
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.Pq Do md Dc or Do md[0-9]* Dc
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and
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.Dq file
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is specified in
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.Fa fs_mntopts ,
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an
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.Xr md 4
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device is created with the specified file used as backing store,
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and then the new device is used as swap space.
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Swap entries on
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.Pa .eli
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devices will cause automatic creation of encrypted devices.
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The
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.Dq ealgo ,
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.Dq aalgo ,
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.Dq keylength ,
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and
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.Dq sectorsize
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options may be passed to control those
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.Xr geli 8
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parameters.
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The fields other than
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.Fa fs_spec
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and
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.Fa fs_type
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are unused.
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If
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.Fa fs_type
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is specified as
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.Dq xx
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the entry is ignored.
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This is useful to show disk partitions which are currently unused.
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.Pp
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The fifth field,
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.Pq Fa fs_freq ,
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is used for these file systems by the
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.Xr dump 8
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command to determine which file systems need to be dumped.
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If the fifth field is not present, a value of zero is returned and
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.Nm dump
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will assume that the file system does not need to be dumped.
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If the fifth field is greater than 0, then it specifies the number of days
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between dumps for this file system.
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.Pp
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The sixth field,
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.Pq Fa fs_passno ,
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is used by the
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.Xr fsck 8
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and
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.Xr quotacheck 8
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programs to determine the order in which file system and quota
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checks are done at reboot time.
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The
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.Fa fs_passno
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field can be any value between 0 and
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.Ql INT_MAX Ns -1 .
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.Pp
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The root file system should be specified with a
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.Fa fs_passno
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of 1, and other file systems should have a
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.Fa fs_passno
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of 2 or greater.
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A file system with a
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.Fa fs_passno
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value of 1 is always checked sequentially and be completed before
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another file system is processed, and it will be processed before
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all file systems with a larger
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.Fa fs_passno .
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.Pp
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For any given value of
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.Fa fs_passno ,
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file systems within a drive will be checked sequentially,
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but file systems on different drives will be checked at the
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same time to utilize parallelism available in the hardware.
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Once all file system checks are complete for the current
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.Fa fs_passno ,
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the same process will start over for the next
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.Fa fs_passno .
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.Pp
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If the sixth field is not present or is zero,
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a value of zero is returned and
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.Xr fsck 8
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and
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.Xr quotacheck 8
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will assume that the file system does not need to be checked.
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.Pp
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The
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.Fa fs_passno
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field can be used to implement finer control when
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the system utilities may determine that the file system resides
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on a different physical device, when it actually does not, as with a
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.Xr ccd 4
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device.
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All file systems with a lower
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.Fa fs_passno
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value will be completed before starting on file systems with a
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higher
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.Fa fs_passno
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value.
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E.g. all file systems with a
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.Fa fs_passno
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of 2 will be completed before any file systems with a
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.Fa fs_passno
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of 3 or greater are started.
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Gaps are allowed between the different
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.Fa fs_passno
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values.
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E.g. file systems listed in
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.Pa /etc/fstab
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may have
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.Fa fs_passno
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values such as 0, 1, 2, 15, 100, 200, 300, and may appear in any order
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within
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.Pa /etc/fstab .
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.Bd -literal
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#define FSTAB_RW "rw" /* read/write device */
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#define FSTAB_RQ "rq" /* read/write with quotas */
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#define FSTAB_RO "ro" /* read-only device */
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#define FSTAB_SW "sw" /* swap device */
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#define FSTAB_XX "xx" /* ignore totally */
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struct fstab {
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char *fs_spec; /* block special device name */
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char *fs_file; /* file system path prefix */
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char *fs_vfstype; /* File system type, ufs, nfs */
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char *fs_mntops; /* Mount options ala -o */
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char *fs_type; /* FSTAB_* from fs_mntops */
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int fs_freq; /* dump frequency, in days */
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int fs_passno; /* pass number on parallel fsck */
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};
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.Ed
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.Pp
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The proper way to read records from
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.Pa fstab
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is to use the routines
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.Xr getfsent 3 ,
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.Xr getfsspec 3 ,
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.Xr getfstype 3 ,
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and
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.Xr getfsfile 3 .
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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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The file
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.Nm
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resides in
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.Pa /etc .
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.El
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.Sh SEE ALSO
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.Xr getfsent 3 ,
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.Xr getvfsbyname 3 ,
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.Xr ccd 4 ,
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.Xr dump 8 ,
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.Xr fsck 8 ,
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.Xr geli 8 ,
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.Xr mount 8 ,
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.Xr quotacheck 8 ,
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.Xr quotaon 8 ,
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.Xr strunvis 3 ,
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.Xr swapon 8 ,
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.Xr umount 8
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.Sh HISTORY
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The
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.Nm
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file format appeared in
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.Bx 4.0 .
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