196 lines
5.0 KiB
Groff
196 lines
5.0 KiB
Groff
.\"
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.\" Copyright (c) 2011-2023 Craig Small <csmall@dropbear.xyz>
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.\" Copyright (c) 2013-2023 Jim Warner <james.warner@comcast.net>
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.\" Copyright (c) 2011-2012 Sami Kerola <kerolasa@iki.fi>
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.\" Copyright (c) 2004-2006 Albert Cahalan
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.\" Copyright (c) 1999 George Staikos <staikos@0wned.org>
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.\"
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.\" This program is free software; you can redistribute it and/or modify
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.\" it under the terms of the GNU General Public License as published by
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.\" the Free Software Foundation; either version 2 of the License, or
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.\" (at your option) any later version.
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.\"
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.\"
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.TH SYSCTL "8" "2023-01-16" "procps-ng" "System Administration"
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.SH NAME
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sysctl \- configure kernel parameters at runtime
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.SH SYNOPSIS
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.B sysctl
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[\fIoptions\fR] [\fIvariable\fR[\fB=\fIvalue\fR]] [...]
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.br
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.B sysctl \-p
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[\fIfile\fR or \fIregexp\fR] [...]
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.SH DESCRIPTION
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.B sysctl
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is used to modify kernel parameters at runtime. The parameters available
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are those listed under \fI/proc/sys/\fR. Procfs is required for
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.B sysctl
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support in Linux. You can use
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.B sysctl
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to both read and write sysctl data.
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.SH PARAMETERS
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.TP
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.I variable
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The name of a key to read from. An example is kernel.ostype. The '/'
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separator is also accepted in place of a '.'.
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.TP
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.IR variable = value
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To set a key, use the form
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.IR variable = value
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where
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.I variable
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is the key and
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.I value
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is the value to set it to. If the value contains quotes or characters
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which are parsed by the shell, you may need to enclose the value in double
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quotes.
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.TP
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\fB\-n\fR, \fB\-\-values\fR
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Use this option to disable printing of the key name when printing values.
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.TP
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\fB\-e\fR, \fB\-\-ignore\fR
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Use this option to ignore errors about unknown keys.
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.TP
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\fB\-N\fR, \fB\-\-names\fR
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Use this option to only print the names. It may be useful with shells that
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have programmable completion.
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.TP
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\fB\-q\fR, \fB\-\-quiet\fR
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Use this option to not display the values set to stdout.
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.TP
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\fB\-w\fR, \fB\-\-write\fR
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Use this option when all arguments prescribe a key to be set.
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.TP
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\fB\-p\fR[\fIFILE\fR], \fB\-\-load\fR[=\fIFILE\fR]
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Load in \fBsysctl\fR settings from the file specified or \fI/etc/sysctl.conf\fR
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if none given. Specifying \- as filename means reading data from standard
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input. Using this option will mean arguments to
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.B sysctl
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are files, which are read in the order they are specified.
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The file argument may be specified as regular expression.
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.TP
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\fB\-a\fR, \fB\-\-all\fR
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Display all values currently available.
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.TP
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\fB\-\-deprecated\fR
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Include deprecated parameters to
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.B \-\-all
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values listing.
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.TP
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\fB\-b\fR, \fB\-\-binary\fR
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Print value without new line.
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.TP
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\fB\-\-system\fR
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Load settings from all system configuration files. See the
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.B SYSTEM FILE PRECEDENCE
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section below.
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.TP
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\fB\-r\fR, \fB\-\-pattern\fR \fIpattern\fR
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Only apply settings that match
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.IR pattern .
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The
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.I pattern
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uses extended regular expression syntax.
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.TP
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\fB\-A\fR
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Alias of \fB\-a\fR
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.TP
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\fB\-d\fR
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Alias of \fB\-h\fR
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.TP
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\fB\-f\fR
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Alias of \fB\-p\fR
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.TP
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\fB\-X\fR
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Alias of \fB\-a\fR
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.TP
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\fB\-o\fR
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Does nothing, exists for BSD compatibility.
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.TP
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\fB\-x\fR
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Does nothing, exists for BSD compatibility.
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.TP
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\fB\-h\fR, \fB\-\-help\fR
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Display help text and exit.
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.TP
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\fB\-V\fR, \fB\-\-version\fR
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Display version information and exit.
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.SH SYSTEM FILE PRECEDENCE
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When using the \fB\-\-system\fR option,
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.B sysctl
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will read files from directories in the following list in given
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order from top to bottom. Once a file of a given filename is loaded, any
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file of the same name in subsequent directories is ignored.
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/etc/sysctl.d/*.conf
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.br
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/run/sysctl.d/*.conf
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.br
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/usr/local/lib/sysctl.d/*.conf
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.br
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/usr/lib/sysctl.d/*.conf
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.br
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/lib/sysctl.d/*.conf
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.br
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/etc/sysctl.conf
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All configuration files are sorted in lexicographic order, regardless of the
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directory they reside in. Configuration files can either be completely
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replaced (by having a new configuration file with the same name in a
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directory of higher priority) or partially replaced (by having a configuration
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file that is ordered later).
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.SH EXAMPLES
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/sbin/sysctl \-a
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.br
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/sbin/sysctl \-n kernel.hostname
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.br
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/sbin/sysctl \-w kernel.domainname="example.com"
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.br
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/sbin/sysctl \-p/etc/sysctl.conf
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.br
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/sbin/sysctl \-a \-\-pattern forward
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.br
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/sbin/sysctl \-a \-\-pattern forward$
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.br
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/sbin/sysctl \-a \-\-pattern 'net.ipv4.conf.(eth|wlan)0.arp'
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.br
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/sbin/sysctl \-\-pattern '\[char94]net.ipv6' \-\-system
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.SH DEPRECATED PARAMETERS
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The
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.B base_reachable_time
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and
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.B retrans_time
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are deprecated. The
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.B sysctl
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command does not allow changing values of these
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parameters. Users who insist to use deprecated kernel interfaces should push values
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to \fB/proc\fR file system by other means. For example:
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.PP
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echo 256 > /proc/sys/net/ipv6/neigh/eth0/base_reachable_time
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.SH FILES
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.I /proc/sys
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.br
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.I /etc/sysctl.d/*.conf
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.br
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.I /run/sysctl.d/*.conf
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.br
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.I /usr/local/lib/sysctl.d/*.conf
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.br
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.I /usr/lib/sysctl.d/*.conf
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.br
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.I /lib/sysctl.d/*.conf
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.br
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.I /etc/sysctl.conf
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.SH SEE ALSO
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.BR proc (5),
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.BR sysctl.conf (5),
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.BR regex (7)
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.SH AUTHOR
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.UR staikos@0wned.org
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George Staikos
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.UE
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.SH "REPORTING BUGS"
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Please send bug reports to
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.UR procps@freelists.org
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.UE
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