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https://github.com/systemd/systemd-stable.git
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12b42c7667
This did not really work out as we had hoped. Trying to do this upstream introduced several problems that probably makes it better suited as a downstream patch after all. At any rate, it is not releaseable in the current state, so we at least need to revert this before the release. * by adjusting the path to binaries, but not do the same thing to the search path we end up with inconsistent man-pages. Adjusting the search path too would be quite messy, and it is not at all obvious that this is worth the effort, but at any rate it would have to be done before we could ship this. * this means that distributed man-pages does not make sense as they depend on config options, and for better or worse we are still distributing man pages, so that is something that definitely needs sorting out before we could ship with this patch. * we have long held that split-usr is only minimally supported in order to boot, and something we hope will eventually go away. So before we start adding even more magic/effort in order to make this work nicely, we should probably question if it makes sense at all.
153 lines
5.4 KiB
XML
153 lines
5.4 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2011 Lennart Poettering
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Copyright 2013 Tom Gundersen
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="nss-myhostname" conditional='HAVE_MYHOSTNAME'>
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<refentryinfo>
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<title>nss-myhostname</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>nss-myhostname</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>nss-myhostname</refname>
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<refname>libnss_myhostname.so.2</refname>
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<refpurpose>Provide hostname resolution for the locally
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configured system hostname.</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>libnss_myhostname.so.2</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>nss-myhostname</command> is a plugin for the GNU
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Name Service Switch (NSS) functionality of the GNU C Library
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(<command>glibc</command>) primarily providing hostname resolution
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for the locally configured system hostname as returned by
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<citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>.
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The precise hostnames resolved by this module are:</para>
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<itemizedlist>
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<listitem><para>The local, configured hostname is resolved to
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all locally configured IP addresses ordered by their scope, or
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— if none are configured — the IPv4 address 127.0.0.2 (which
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is on the local loopback) and the IPv6 address ::1 (which is the
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local host).</para></listitem>
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<listitem><para>The hostname <literal>localhost</literal> is
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resolved to the IP addresses 127.0.0.1 and
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::1.</para></listitem>
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<listitem><para>The hostname <literal>gateway</literal> is
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resolved to all current default routing gateway addresses,
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ordered by their metric. This assigns a stable hostname to the
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current gateway, useful for referencing it independently of the
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current network configuration state.</para></listitem>
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</itemizedlist>
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<para>Various software relies on an always-resolvable local
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hostname. When using dynamic hostnames, this is traditionally
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achieved by patching <filename>/etc/hosts</filename> at the same
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time as changing the hostname. This is problematic since it
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requires a writable <filename>/etc</filename> file system and is
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fragile because the file might be edited by the administrator at
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the same time. With <command>nss-myhostname</command> enabled
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changing <filename>/etc/hosts</filename> is unnecessary, and on
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many systems the file becomes entirely optional.</para>
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<para>To activate the NSS modules, <literal>myhostname</literal>
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has to be added to the line starting with
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<literal>hosts:</literal> in
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<filename>/etc/nsswitch.conf</filename>.</para>
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<para>It is recommended to place <literal>myhostname</literal>
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last in the <filename>nsswitch.conf</filename> line to make sure
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that this mapping is only used as fallback, and any DNS or
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<filename>/etc/hosts</filename> based mapping takes
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precedence.</para>
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</refsect1>
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<refsect1>
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<title>Example</title>
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<para>Here's an example <filename>/etc/nsswitch.conf</filename>
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file, that enables <command>myhostname</command> correctly:</para>
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<programlisting>passwd: compat
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group: compat
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shadow: compat
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hosts: files dns mymachines <command>myhostname</command>
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networks: files
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protocols: db files
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services: db files
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ethers: db files
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rpc: db files
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netgroup: nis</programlisting>
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<para>To test, use <command>glibc</command>'s <command>getent</command> tool:</para>
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<programlisting>$ getent ahosts `hostname`
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::1 STREAM omega
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::1 DGRAM
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::1 RAW
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127.0.0.2 STREAM
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127.0.0.2 DGRAM
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127.0.0.2 RAW</programlisting>
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<para>In this case the local hostname is <varname>omega</varname>.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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