man/environment.d.xml

   1 <?xml version="1.0"?>
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   3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1-or-later
   7
   8   Copyright © 2016 Red Hat, Inc.
   9 -->
  10 <refentry id="environment.d" conditional='ENABLE_ENVIRONMENT_D'
  11     xmlns:xi="http://www.w3.org/2001/XInclude">
  12
  13   <refentryinfo>
  14     <title>environment.d</title>
  15     <productname>systemd</productname>
  16   </refentryinfo>
  17
  18   <refmeta>
  19     <refentrytitle>environment.d</refentrytitle>
  20     <manvolnum>5</manvolnum>
  21   </refmeta>
  22
  23   <refnamediv>
  24     <refname>environment.d</refname>
  25     <refpurpose>Definition of user service environment</refpurpose>
  26   </refnamediv>
  27
  28   <refsynopsisdiv>
  29     <para><simplelist>
  30       <member><filename>~/.config/environment.d/*.conf</filename></member>
  31       <member><filename>/etc/environment.d/*.conf</filename></member>
  32       <member><filename>/run/environment.d/*.conf</filename></member>
  33       <member><filename>/usr/local/lib/environment.d/*.conf</filename></member>
  34       <member><filename>/usr/lib/environment.d/*.conf</filename></member>
  35       <member><filename>/etc/environment</filename></member>
  36     </simplelist></para>
  37   </refsynopsisdiv>
  38
  39   <refsect1>
  40     <title>Description</title>
  41
  42     <para>Configuration files in the <filename>environment.d/</filename> directories contain lists of
  43     environment variable assignments passed to services started by the systemd user instance.
  44     <citerefentry><refentrytitle>systemd-environment-d-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  45     parses them and updates the environment exported by the systemd user instance. See below for an
  46     discussion of which processes inherit those variables.</para>
  47
  48     <para>It is recommended to use numerical prefixes for file names to simplify ordering.</para>
  49
  50     <para>For backwards compatibility, a symlink to <filename>/etc/environment</filename> is
  51     installed, so this file is also parsed.</para>
  52   </refsect1>
  53
  54   <xi:include href="standard-conf.xml" xpointer="confd" />
  55
  56   <refsect1>
  57     <title>Configuration Format</title>
  58
  59     <para>The configuration files contain a list of
  60     <literal><replaceable>KEY</replaceable>=<replaceable>VALUE</replaceable></literal> environment
  61     variable assignments, separated by newlines. The right hand side of these assignments may
  62     reference previously defined environment variables, using the <literal>${OTHER_KEY}</literal>
  63     and <literal>$OTHER_KEY</literal> format. It is also possible to use
  64     <literal>${<replaceable>FOO</replaceable>:-<replaceable>DEFAULT_VALUE</replaceable>}</literal>
  65     to expand in the same way as <literal>${<replaceable>FOO</replaceable>}</literal> unless the
  66     expansion would be empty, in which case it expands to <replaceable>DEFAULT_VALUE</replaceable>,
  67     and use
  68     <literal>${<replaceable>FOO</replaceable>:+<replaceable>ALTERNATE_VALUE</replaceable>}</literal>
  69     to expand to <replaceable>ALTERNATE_VALUE</replaceable> as long as
  70     <literal>${<replaceable>FOO</replaceable>}</literal> would have expanded to a non-empty value.
  71     No other elements of shell syntax are supported.</para>
  72
  73     <para>Each <replaceable>KEY</replaceable> must be a valid variable name. Empty lines
  74     and lines beginning with the comment character <literal>#</literal> are ignored.</para>
  75
  76     <refsect2>
  77       <title>Example</title>
  78       <example>
  79         <title>Setup environment to allow access to a program installed in
  80         <filename index="false">/opt/foo</filename></title>
  81
  82         <para><filename index="false">/etc/environment.d/60-foo.conf</filename>:
  83         </para>
  84         <programlisting>
  85         FOO_DEBUG=force-software-gl,log-verbose
  86         PATH=/opt/foo/bin:$PATH
  87         LD_LIBRARY_PATH=/opt/foo/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
  88         XDG_DATA_DIRS=/opt/foo/share:${XDG_DATA_DIRS:-/usr/local/share/:/usr/share/}
  89 </programlisting>
  90       </example>
  91     </refsect2>
  92   </refsect1>
  93
  94   <refsect1>
  95     <title>Applicability</title>
  96
  97     <para>Environment variables exported by the user service manager (<command>systemd --user</command>
  98     instance started in the <filename>user@<replaceable>uid</replaceable>.service</filename> system service)
  99     are passed to any services started by that service manager. In particular, this may include services
 100     which run user shells. For example in the GNOME environment, the graphical terminal emulator runs as the
 101     <filename>gnome-terminal-server.service</filename> user unit, which in turn runs the user shell, so that
 102     shell will inherit environment variables exported by the user manager. For other instances of the shell,
 103     not launched by the user service manager, the environment they inherit is defined by the program that
 104     starts them. Hint: in general,
 105     <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry> units
 106     contain programs launched by systemd, and
 107     <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry> units
 108     contain programs launched by something else.</para>
 109
 110     <para>Note that these files do not affect the environment block of the service manager itself, but
 111     exclusively the environment blocks passed to the services it manages. Environment variables set that way
 112     thus cannot be used to influence behaviour of the service manager. In order to make changes to the
 113     service manager's environment block the environment must be modified before the user's service manager is
 114     invoked, for example from the system service manager or via a PAM module.</para>
 115
 116     <para>Specifically, for ssh logins, the
 117     <citerefentry project='man-pages'><refentrytitle>sshd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 118     service builds an environment that is a combination of variables forwarded from the remote system and
 119     defined by <command>sshd</command>, see the discussion in
 120     <citerefentry project='man-pages'><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
 121     A graphical display session will have an analogous mechanism to define the environment. Note that some
 122     managers query the systemd user instance for the exported environment and inject this configuration into
 123     programs they start, using <command>systemctl show-environment</command> or the underlying D-Bus call.
 124     </para>
 125   </refsect1>
 126
 127   <refsect1>
 128     <title>See Also</title>
 129     <para><simplelist type="inline">
 130       <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
 131       <member><citerefentry><refentrytitle>systemd-environment-d-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
 132       <member><citerefentry><refentrytitle>systemd.environment-generator</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
 133     </simplelist></para>
 134   </refsect1>
 135
 136 </refentry>