a395137acd
Added note into sysctl.8 manpage about directory precedence. This information may be important for users who create new config files at several destinations. Especially the information about files to be omitted in directories with lower priority shall be given.
169 lines
4.3 KiB
Groff
169 lines
4.3 KiB
Groff
.\" Copyright 1999, George Staikos (staikos@0wned.org)
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.\" This file may be used subject to the terms and conditions of the
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.\" GNU General Public License Version 2, or any later version
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.\" at your option, as published by the Free Software Foundation.
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.\" This program is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details."
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.TH SYSCTL "8" "Jan 2012" "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 /proc/sys/. 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. This requires the
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.B \-w
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parameter to use.
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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 you want to change a sysctl setting.
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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 sysctl settings from the file specified or /etc/sysctl.conf if none
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given. Specifying \- as filename means reading data from standard input.
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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. Files are read from
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directories in the following list in given order from top to bottom.
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Once a file of a given filename is loaded, any file of the same name
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in subsequent directories is ignored.
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.br
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/run/sysctl.d/*.conf
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.br
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/etc/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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.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 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 \-\-system \-\-pattern '^net.ipv6'
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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 sysctl 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 /proc 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.conf
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.SH SEE ALSO
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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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