man: Factor out a common snippet for .d directories and precedence

Several manpages contain duplicate text describing a standard set of .d
configuration directories, with the usual sorting, precedence,
overrides, and so on.  Factor this common text out using XInclude before
proliferating it even further.

1 files changed, 45 insertions, 0 deletions

diff --git a/man/standard-conf.xml b/man/standard-conf.xml
new file mode 100644
index 000000000..b87d7e955
--- /dev/null
+++ b/man/standard-conf.xml
@@ -0,0 +1,45 @@
+<?xml version="1.0"?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
+<!DOCTYPE refsection PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+          "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
+
+<refsection>
+  <refsection id='confd'>
+    <title>Configuration Directories and Precedence</title>
+
+    <para>Configuration files are read from directories in
+    <filename>/etc/</filename>, <filename>/run/</filename>, and
+    <filename>/usr/lib/</filename>, in order of precedence.
+    Each configuration file in these configuration directories shall be named in
+    the style of <filename><replaceable>filename</replaceable>.conf</filename>.
+    Files in <filename>/etc/</filename> override files with the same name in
+    <filename>/run/</filename> and <filename>/usr/lib/</filename>. Files in
+    <filename>/run/</filename> override files with the same name in
+    <filename>/usr/lib/</filename>.</para>
+
+    <para>Packages should install their configuration files in
+    <filename>/usr/lib/</filename>. Files in <filename>/etc/</filename> are
+    reserved for the local administrator, who may use this logic to override the
+    configuration files installed by vendor packages. All configuration files
+    are sorted by their filename in lexicographic order, regardless of which of
+    the directories they reside in. If multiple files specify the same option,
+    the entry in the file with the lexicographically latest name will take
+    precedence. It is recommended to prefix all filenames with a two-digit number
+    and a dash, to simplify the ordering of the files.</para>
+
+    <para>If the administrator wants to disable a configuration file supplied by
+    the vendor, the recommended way is to place a symlink to
+    <filename>/dev/null</filename> in the configuration directory in
+    <filename>/etc/</filename>, with the same filename as the vendor
+    configuration file.</para>
+  </refsection>
+
+  <refsection id='conf'>
+    <title>Configuration File</title>
+
+    <para>Configuration is also read from a single configuration file in
+    <filename>/etc/</filename>. This file is read before any of the
+    configuration directories, and has the lowest precedence; entries in a file
+    in any configuration directory override entries in the single configuration
+    file.</para>
+  </refsection>
+</refsection>