man/environment.d.xml

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<refentry id="environment.d" conditional='ENABLE_ENVIRONMENT_D'
    xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>environment.d</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>environment.d</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>environment.d</refname>
    <refpurpose>Definition of user session environment</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><filename>~/.config/environment.d/*.conf</filename></para>
    <para><filename>/etc/environment.d/*.conf</filename></para>
    <para><filename>/run/environment.d/*.conf</filename></para>
    <para><filename>/usr/lib/environment.d/*.conf</filename></para>
    <para><filename>/etc/environment</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>The <filename>environment.d</filename> directories contain a list of "global" environment
    variable assignments for the user environment.
    <citerefentry><refentrytitle>systemd-environment-d-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    parses them and updates the environment exported by the systemd user instance to the services it
    starts.</para>

    <para>It is recommended to use numerical prefixes for file names to simplify ordering.</para>

    <para>For backwards compatibility, a symlink to <filename>/etc/environment</filename> is
    installed, so this file is also parsed.</para>
  </refsect1>

  <xi:include href="standard-conf.xml" xpointer="confd" />

  <refsect1>
    <title>Configuration Format</title>

    <para>The configuration files contain a list of
    <literal><replaceable>KEY</replaceable>=<replaceable>VALUE</replaceable></literal> environment
    variable assignments, separated by newlines. The right hand side of these assignments may
    reference previously defined environment variables, using the <literal>${OTHER_KEY}</literal>
    and <literal>$OTHER_KEY</literal> format. It is also possible to use

    <literal>${<replaceable>FOO</replaceable>:-<replaceable>DEFAULT_VALUE</replaceable>}</literal>
    to expand in the same way as <literal>${<replaceable>FOO</replaceable>}</literal> unless the
    expansion would be empty, in which case it expands to <replaceable>DEFAULT_VALUE</replaceable>,
    and use
    <literal>${<replaceable>FOO</replaceable>:+<replaceable>ALTERNATE_VALUE</replaceable>}</literal>
    to expand to <replaceable>ALTERNATE_VALUE</replaceable> as long as
    <literal>${<replaceable>FOO</replaceable>}</literal> would have expanded to a non-empty value.
    No other elements of shell syntax are supported.</para>

    <para>Each <replaceable>KEY</replaceable> must be a valid variable name. Empty lines
    and lines beginning with the comment character <literal>#</literal> are ignored.</para>

    <refsect2>
      <title>Example</title>
      <example>
        <title>Setup environment to allow access to a program installed in
        <filename noindex='true'>/opt/foo</filename></title>

        <para><filename>/etc/environment.d/60-foo.conf</filename>:
        </para>
        <programlisting>
        FOO_DEBUG=force-software-gl,log-verbose
        PATH=/opt/foo/bin:$PATH
        LD_LIBRARY_PATH=/opt/foo/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
        XDG_DATA_DIRS=/opt/foo/share:${XDG_DATA_DIRS:-/usr/local/share/:/usr/share/}
        </programlisting>
      </example>
    </refsect2>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-environment-d-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.environment-generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>