man/environment.d.xml

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   8   Copyright © 2016 Red Hat, Inc.
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  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 session environment</refpurpose>
  26   </refnamediv>
  27
  28   <refsynopsisdiv>
  29     <para><filename>~/.config/environment.d/*.conf</filename></para>
  30     <para><filename>/etc/environment.d/*.conf</filename></para>
  31     <para><filename>/run/environment.d/*.conf</filename></para>
  32     <para><filename>/usr/lib/environment.d/*.conf</filename></para>
  33     <para><filename>/etc/environment</filename></para>
  34   </refsynopsisdiv>
  35
  36   <refsect1>
  37     <title>Description</title>
  38
  39     <para>The <filename>environment.d</filename> directories contain a list of environment variable
  40     assignments for services started by the systemd user instance.
  41     <citerefentry><refentrytitle>systemd-environment-d-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  42     parses them and updates the environment exported by the systemd user instance. See below for an
  43     discussion of which processes inherit those variables.</para>
  44
  45     <para>It is recommended to use numerical prefixes for file names to simplify ordering.</para>
  46
  47     <para>For backwards compatibility, a symlink to <filename>/etc/environment</filename> is
  48     installed, so this file is also parsed.</para>
  49   </refsect1>
  50
  51   <xi:include href="standard-conf.xml" xpointer="confd" />
  52
  53   <refsect1>
  54     <title>Configuration Format</title>
  55
  56     <para>The configuration files contain a list of
  57     <literal><replaceable>KEY</replaceable>=<replaceable>VALUE</replaceable></literal> environment
  58     variable assignments, separated by newlines. The right hand side of these assignments may
  59     reference previously defined environment variables, using the <literal>${OTHER_KEY}</literal>
  60     and <literal>$OTHER_KEY</literal> format. It is also possible to use
  61
  62     <literal>${<replaceable>FOO</replaceable>:-<replaceable>DEFAULT_VALUE</replaceable>}</literal>
  63     to expand in the same way as <literal>${<replaceable>FOO</replaceable>}</literal> unless the
  64     expansion would be empty, in which case it expands to <replaceable>DEFAULT_VALUE</replaceable>,
  65     and use
  66     <literal>${<replaceable>FOO</replaceable>:+<replaceable>ALTERNATE_VALUE</replaceable>}</literal>
  67     to expand to <replaceable>ALTERNATE_VALUE</replaceable> as long as
  68     <literal>${<replaceable>FOO</replaceable>}</literal> would have expanded to a non-empty value.
  69     No other elements of shell syntax are supported.</para>
  70
  71     <para>Each <replaceable>KEY</replaceable> must be a valid variable name. Empty lines
  72     and lines beginning with the comment character <literal>#</literal> are ignored.</para>
  73
  74     <refsect2>
  75       <title>Example</title>
  76       <example>
  77         <title>Setup environment to allow access to a program installed in
  78         <filename index="false">/opt/foo</filename></title>
  79
  80         <para><filename>/etc/environment.d/60-foo.conf</filename>:
  81         </para>
  82         <programlisting>
  83         FOO_DEBUG=force-software-gl,log-verbose
  84         PATH=/opt/foo/bin:$PATH
  85         LD_LIBRARY_PATH=/opt/foo/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
  86         XDG_DATA_DIRS=/opt/foo/share:${XDG_DATA_DIRS:-/usr/local/share/:/usr/share/}
  87         </programlisting>
  88       </example>
  89     </refsect2>
  90   </refsect1>
  91
  92   <refsect1>
  93     <title>Applicability</title>
  94
  95     <para>Environment variables exported by the user manager (<command>systemd --user</command> instance
  96     started in the <filename>user@<replaceable>uid</replaceable>.service</filename> system service) apply to
  97     any services started by that manager. In particular, this may include services which run user shells. For
  98     example in the Gnome environment, the graphical terminal emulator runs as the
  99     <filename>gnome-terminal-server.service</filename> user unit, which in turn runs the user shell, so that
 100     shell will inherit environment variables exported by the user manager. For other instances of the shell,
 101     not launched by the user manager, the environment they inherit is defined by the program that starts
 102     them. Hint: in general,
 103     <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 104     units contain programs launched by systemd, and
 105     <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 106     units contain programs launched by something else.</para>
 107
 108     <para>Specifically, for ssh logins, the
 109     <citerefentry project='die-net'><refentrytitle>sshd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 110     service builds an environment that is a combination of variables forwarded from the remote system and
 111     defined by <command>sshd</command>, see the discussion in
 112     <citerefentry project='die-net'><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
 113     A graphical display session will have an analogous mechanism to define the environment. Note that some
 114     managers query the systemd user instance for the exported environment and inject this configuration into
 115     programs they start, using <command>systemctl show-environment</command> or the underlying D-Bus call.
 116     </para>
 117   </refsect1>
 118
 119   <refsect1>
 120     <title>See Also</title>
 121     <para>
 122       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 123       <citerefentry><refentrytitle>systemd-environment-d-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 124       <citerefentry><refentrytitle>systemd.environment-generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 125     </para>
 126   </refsect1>
 127
 128 </refentry>