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systemd/man/sysctl.d.xml
Filipe Brandenburger 681eb9cf2b man: generate configured paths in manpages
In particular, use /lib/systemd instead of /usr/lib/systemd in distributions
like Debian which still have not adopted a /usr merge setup.

Use XML entities from man/custom-entities.ent to replace configured paths while
doing XSLT processing of the original XML files. There was precedent of some
files (such as systemd.generator.xml) which were already using this approach.

This addresses most of the (manual) fixes from this patch:
http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/patches/Fix-paths-in-man-pages.patch?h=experimental-220

The idea of using generic XML entities was presented here:
http://lists.freedesktop.org/archives/systemd-devel/2015-May/032240.html

This patch solves almost all the issues, with the exception of:
- Path to /bin/mount and /bin/umount.
- Generic statements about preference of /lib over /etc.

These will be handled separately by follow up patches.

Tested:
- With default configure settings, ran "make install" to two separate
  directories and compared the output to confirm they matched exactly.
- Used a set of configure flags including $CONFFLAGS from Debian:
  http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/rules
  Installed the tree and confirmed the paths use /lib/systemd instead of
  /usr/lib/systemd and that no other unexpected differences exist.
- Confirmed that `make distcheck` still passes.
2015-05-28 19:28:19 +02:00

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XML

<?xml version="1.0"?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
<!ENTITY % entities SYSTEM "custom-entities.ent" >
%entities;
]>
<!--
This file is part of systemd.
Copyright 2011 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sysctl.d"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sysctl.d</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sysctl.d</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>sysctl.d</refname>
<refpurpose>Configure kernel parameters at boot</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>/etc/sysctl.d/*.conf</filename></para>
<para><filename>/run/sysctl.d/*.conf</filename></para>
<para><filename>/usr/lib/sysctl.d/*.conf</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>At boot,
<citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
reads configuration files from the above directories to configure
<citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
kernel parameters.</para>
</refsect1>
<refsect1>
<title>Configuration Format</title>
<para>The configuration files contain a list of variable
assignments, separated by newlines. Empty lines and lines whose
first non-whitespace character is <literal>#</literal> or
<literal>;</literal> are ignored.</para>
<para>Note that either <literal>/</literal> or
<literal>.</literal> may be used as separators within sysctl
variable names. If the first separator is a slash, remaining
slashes and dots are left intact. If the first separator is a dot,
dots and slashes are interchanged.
<literal>kernel.domainname=foo</literal> and
<literal>kernel/domainname=foo</literal> are equivalent and will
cause <literal>foo</literal> to be written to
<filename>/proc/sys/kernel/domainname</filename>. Either
<literal>net.ipv4.conf.enp3s0/200.forwarding</literal> or
<literal>net/ipv4/conf/enp3s0.200/forwarding</literal> may be used
to refer to
<filename>/proc/sys/net/ipv4/conf/enp3s0.200/forwarding</filename>.
</para>
<para>The settings configured with <filename>sysctl.d</filename>
files will be applied early on boot. The network
interface-specific options will also be applied individually for
each network interface as it shows up in the system. (More
specifically, <filename>net.ipv4.conf.*</filename>,
<filename>net.ipv6.conf.*</filename>,
<filename>net.ipv4.neigh.*</filename> and
<filename>net.ipv6.neigh.*</filename>).</para>
<para>Many sysctl parameters only become available when certain
kernel modules are loaded. Modules are usually loaded on demand,
e.g. when certain hardware is plugged in or network brought up.
This means that
<citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
which runs during early boot will not configure such parameters if
they become available after it has run. To set such parameters, it
is recommended to add an
<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>
rule to set those parameters when they become available.
Alternatively, a slightly simpler and less efficient option is to
add the module to
<citerefentry><refentrytitle>modules-load.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
causing it to be loaded statically before sysctl settings are
applied (see example below).</para>
</refsect1>
<xi:include href="standard-conf.xml" xpointer="confd" />
<refsect1>
<title>Examples</title>
<example>
<title>Set kernel YP domain name</title>
<para><filename>/etc/sysctl.d/domain-name.conf</filename>:
</para>
<programlisting>kernel.domainname=example.com</programlisting>
</example>
<example>
<title>Disable packet filter on bridged packets (method one)</title>
<para><filename>/etc/udev/rules.d/99-bridge.rules</filename>:
</para>
<programlisting>ACTION=="add", SUBSYSTEM=="module", KERNEL=="bridge", RUN+="&rootlibexecdir;/systemd-sysctl --prefix=/net/bridge"
</programlisting>
<para><filename>/etc/sysctl.d/bridge.conf</filename>:
</para>
<programlisting>net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0
</programlisting>
</example>
<example>
<title>Disable packet filter on bridged packets (method two)</title>
<para><filename>/etc/modules-load.d/bridge.conf</filename>:
</para>
<programlisting>bridge</programlisting>
<para><filename>/etc/sysctl.d/bridge.conf</filename>:
</para>
<programlisting>net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0
</programlisting>
</example>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>sysctl.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>modprobe</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>