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0a0c18180c
Reported by: kaktus Reviewed by: kaktus MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D25351
194 lines
5.1 KiB
Groff
194 lines
5.1 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. 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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.\" @(#)umount.8 8.2 (Berkeley) 5/8/95
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.\" $FreeBSD$
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.\"
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.Dd June 19, 2020
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.Dt UMOUNT 8
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.Os
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.Sh NAME
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.Nm umount
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.Nd unmount file systems
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.Sh SYNOPSIS
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.Nm
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.Op Fl fNnv
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.Ar special ... | node ... | fsid ...
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.Nm
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.Fl a | A
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.Op Fl F Ar fstab
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.Op Fl fnv
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.Op Fl h Ar host
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.Op Fl t Ar type
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.Sh DESCRIPTION
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The
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.Nm
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utility calls the
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.Xr unmount 2
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system call to remove a file system from the file system tree.
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The file system can be specified by its
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.Ar special
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device or remote node
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.Pq Ar rhost Ns Cm \& : Ns Ar path ,
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the path to the mount point
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.Ar node
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or by the file system ID
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.Ar fsid
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as reported by
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.Dq mount -v
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when run by root.
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.Pp
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The options are as follows:
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.Bl -tag -width "-F fstab"
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.It Fl a
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All the file systems described in
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.Xr fstab 5
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are unmounted.
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.It Fl A
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All the currently mounted file systems are unmounted,
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except for those mounted at
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.Pa /
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or
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.Pa /dev .
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.It Fl F Ar fstab
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Specify the
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.Pa fstab
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file to use.
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.It Fl f
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The file system is forcibly unmounted.
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Active special devices continue to work,
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but all other files return errors if further accesses are attempted.
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The root file system cannot be forcibly unmounted.
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For NFS, a forced dismount can take up to 1 minute or more to
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complete against an unresponsive server and may throw away
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data not yet written to the server for this case.
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If a process, such as
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.Nm
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without the
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.Fl f
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flag is hung on an
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.Tn NFS
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mount point, use the
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.Fl N
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flag instead.
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Also, doing a forced dismount of an NFSv3 mount when
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.Xr rpc.lockd 8
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is running is unsafe and can result in a crash.
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.It Fl h Ar host
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Only file systems mounted from the specified host will be
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unmounted.
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This option implies the
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.Fl A
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option and, unless otherwise specified with the
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.Fl t
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option, will only unmount
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.Tn NFS
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file systems.
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.It Fl N
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Do a forced dismount of an
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.Tn NFS
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mount point without checking the mount path.
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This option can only be used with the path to the mount point
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.Ar node
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and the path must be specified exactly as it was at mount time.
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This option is useful when a process is hung waiting for an unresponsive
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.Tn NFS
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server while holding a vnode lock on the mounted-on vnode, such that
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.Nm
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with the
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.Fl f
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flag can't complete.
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Using this option can result in a loss of file updates that have not been
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flushed to the
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.Tn NFS
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server.
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.It Fl n
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Unless the
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.Fl f
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is used, the
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.Nm
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will not unmount an active file system.
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It will, however, perform a flush.
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This flag disables this behaviour, preventing the flush
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if there are any files open.
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.It Fl t Ar type
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Is used to indicate the actions should only be taken on
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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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umount -a -t nfs,nullfs
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.Ed
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.Pp
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unmounts all file systems of the type
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.Tn NFS
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and
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.Tn NULLFS
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that are listed in the
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.Xr fstab 5
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file.
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.It Fl v
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Verbose, additional information is printed out as each file system
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is unmounted.
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.El
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.Sh ENVIRONMENT
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.Bl -tag -width ".Ev PATH_FSTAB"
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.It Ev PATH_FSTAB
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If the environment variable
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.Ev PATH_FSTAB
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is set, all operations are performed against the specified file.
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.Ev PATH_FSTAB
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will not be honored if the process environment or memory address space is
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considered
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.Dq tainted .
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(See
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.Xr issetugid 2
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for more information.)
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.El
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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 SEE ALSO
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.Xr unmount 2 ,
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.Xr fstab 5 ,
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.Xr autounmountd 8 ,
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.Xr mount 8
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.Sh HISTORY
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A
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.Nm
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utility appeared in
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.At v1 .
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