core: simplify fd collection code, return number of fds as return value

[thirdparty/systemd.git] / man / systemd-activate.xml

<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<!--
  This file is part of systemd.

  Copyright 2013 Zbigniew Jędrzejewski-Szmek

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->

<refentry id="systemd-activate"
          xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>systemd-activate</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>Developer</contrib>
        <firstname>Zbigniew</firstname>
        <surname>Jędrzejewski-Szmek</surname>
        <email>zbyszek@in.waw.pl</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd-activate</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd-activate</refname>
    <refpurpose>Test socket activation of daemons</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>/usr/lib/systemd/systemd-activate</command>
      <arg choice="opt" rep="repeat">OPTIONS</arg>
      <arg choice="plain"><replaceable>daemon</replaceable></arg>
      <arg choice="opt" rep="repeat">OPTIONS</arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>systemd-activate</command> can be used to
    launch a socket activated daemon from the command line for
    testing purposes. It can also be used to launch single instances
    of the daemon per connection (inetd-style).
    </para>

    <para>The daemon to launch and its options should be specified
    after options intended for <command>systemd-activate</command>.
    </para>

    <para>If the <option>-a</option> option is given, file descriptor
    of the connection will be used as the standard input and output of
    the launched process. Otherwise, standard input and output will be
    inherited, and sockets will be passed through file descriptors 3
    and higher. Sockets passed through <varname>$LISTEN_FDS</varname>
    to <command>systemd-activate</command> will be passed through to
    the daemon, in the original positions. Other sockets specified
    with <option>--listen</option> will use consecutive descriptors.
    </para>
  </refsect1>

  <refsect1>
    <title>Options</title>
    <variablelist>
      <varlistentry>
        <term><option>-l <replaceable>address</replaceable></option></term>
        <term><option>--listen=<replaceable>address</replaceable></option></term>

        <listitem><para>Listen on this <replaceable>address</replaceable>.
        Takes a string like <literal>2000</literal> or
        <literal>127.0.0.1:2001</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-a</option></term>
        <term><option>--accept</option></term>

        <listitem><para>Launch a separate instance of daemon per
        connection and pass the connection socket as standard input
        and standard output.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-E <replaceable>VAR</replaceable><optional>=<replaceable>VALUE</replaceable></optional></option></term>
        <term><option>--setenv=<replaceable>VAR</replaceable><optional>=<replaceable>VALUE</replaceable></optional></option></term>

        <listitem><para>Add this variable to the environment of the
        launched process. If <replaceable>VAR</replaceable> is
        followed by <literal>=</literal>, assume that it is a
        variable–value pair. Otherwise, obtain the value from the
        environment of <command>systemd-activate</command> itself.
        </para></listitem>
      </varlistentry>

      <xi:include href="standard-options.xml" xpointer="help" />
      <xi:include href="standard-options.xml" xpointer="version" />
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Environment variables</title>
    <variablelist class='environment-variables'>
      <varlistentry>
        <term><varname>$LISTEN_FDS</varname></term>
        <term><varname>$LISTEN_PID</varname></term>

        <listitem><para>See
        <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>$SYSTEMD_LOG_TARGET</varname></term>
        <term><varname>$SYSTEMD_LOG_LEVEL</varname></term>
        <term><varname>$SYSTEMD_LOG_COLOR</varname></term>
        <term><varname>$SYSTEMD_LOG_LOCATION</varname></term>

        <listitem><para>Same as in
        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Examples</title>

    <example>
      <title>Run an echo server on port 2000</title>

      <programlisting>$ /usr/lib/systemd/systemd-activate -l 2000 -a cat</programlisting>
    </example>

    <example>
      <title>Run a socket activated instance of <citerefentry><refentrytitle>systemd-journal-gatewayd</refentrytitle><manvolnum>8</manvolnum></citerefentry></title>

      <programlisting>$ /usr/lib/systemd/systemd-activate -l 19531 /usr/lib/systemd/systemd-journal-gatewayd</programlisting>
    </example>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>cat</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    </para>
  </refsect1>
</refentry>