docs/manual/invoking.xml - httpd - Git at Google


            
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            <manualpage metafile="invoking.xml.meta">


              <title>Starting Apache</title>


            <summary>

            
                <p>On Windows, Apache is normally run as a service.

            
                For details, see <a

            
                href="platform/windows.html#winsvc">Running Apache as a Service</a>.

            
                </p>


                <p>On Unix, the <program>httpd</program> program

            
                is run as a daemon that executes continuously in the

            
                background to handle requests.  This document describes how

            
                to invoke <program>httpd</program>.</p>

            
            </summary>


            <seealso><a href="stopping.html">Stopping and Restarting</a></seealso>

            
            <seealso><program>httpd</program></seealso>

            
            <seealso><program>apachectl</program></seealso>


            <section id="startup"><title>How Apache Starts</title>


                <p>If the <directive module="mpm_common">Listen</directive>

            
                specified in the configuration file is default of 80 (or any other

            
                port below 1024), then it is necessary to have root privileges in

            
                order to start apache, so that it can bind to this privileged

            
                port. Once the server has started and performed a few preliminary

            
                activities such as opening its log files, it will launch several

            
                <em>child</em> processes which do the work of listening for and

            
                answering requests from clients. The main <code>httpd</code>

            
                process continues to run as the root user, but the child processes

            
                run as a less privileged user. This is controlled by the selected

            
                <a href="mpm.html">Multi-Processing Module</a>.</p>


                <p>The recommended method of invoking the <program>httpd</program>

            
                executable is to use the <program>apachectl</program> control script. This

            
                script sets certain environment variables that are necessary for

            
                <program>httpd</program> to function correctly under some operating

            
                systems, and then invokes the <program>httpd</program> binary.

            
                <program>apachectl</program> will pass through any command line

            
                arguments, so any <program>httpd</program> options may also be used with

            
                <program>apachectl</program>.  You may also directly edit the

            
                <program>apachectl</program> script by changing the <code>HTTPD</code>

            
                variable near the top to specify the correct location of the

            
                <program>httpd</program> binary and any command-line arguments that you

            
                wish to be <em>always</em> present.</p>


                <p>The first thing that <program>httpd</program> does when it is

            
                invoked is to locate and read the <a

            
                href="configuring.html">configuration file</a>

            
                <code>httpd.conf</code>. The location of this file is set at

            
                compile-time, but it is possible to specify its location at run

            
                time using the <code>-f</code> command-line option as in</p>


            <example>/usr/local/apache2/bin/apachectl -f

            
                  /usr/local/apache2/conf/httpd.conf</example>


                <p>If all goes well during startup, the server will detach from

            
                the terminal and the command prompt will return almost

            
                immediately. This indicates that the server is up and running.

            
                You can then use your browser to connect to the server and view

            
                the test page in the <directive

            
                module="core">DocumentRoot</directive> directory.</p>

            
            </section>


            <section id="errors"><title>Errors During Start-up</title>


                <p>If Apache suffers a fatal problem during startup, it will

            
                write a message describing the problem either to the console or

            
                to the <directive module="core">ErrorLog</directive> before

            
                exiting. One of the most common error messages is "<code>Unable

            
                to bind to Port ...</code>". This message is usually caused by

            
                either:</p>


                <ul>

            
                  <li>Trying to start the server on a privileged port when not

            
                  logged in as the root user; or</li>


                  <li>Trying to start the server when there is another instance

            
                  of Apache or some other web server already bound to the same

            
                  Port.</li>

            
                </ul>


                <p>For further trouble-shooting instructions, consult the

            
                Apache <a href="https://cwiki.apache.org/confluence/display/httpd/FAQ">FAQ</a>.</p>

            
            </section>


            <section id="boot"><title>Starting at Boot-Time</title>


                <p>If you want your server to continue running after a system

            
                reboot, you should add a call to <program>apachectl</program> to your

            
                system startup files (typically <code>rc.local</code> or a file in

            
                an <code>rc.N</code> directory). This will start Apache as

            
                root. Before doing this ensure that your server is properly

            
                configured for security and access restrictions.</p>


                <p>The <program>apachectl</program> script is designed to act like a

            
                standard SysV init script; it can take the arguments

            
                <code>start</code>, <code>restart</code>, and <code>stop</code>

            
                and translate them into the appropriate signals to

            
                <program>httpd</program>.  So you can often simply link

            
                <program>apachectl</program> into the appropriate init directory. But be

            
                sure to check the exact requirements of your system.</p>

            
            </section>


            <section id="info"><title>Additional Information</title>


                <p>Additional information about the command-line options of <program>

            
                httpd</program> and <program>apachectl</program> as well as other support

            
                programs included with the server is available on the

            
                <a href="programs/">Server and Supporting Programs</a> page.

            
                There is also documentation on all the <a

            
                href="mod/">modules</a> included with the Apache distribution

            
                and the <a href="mod/directives.html">directives</a> that they

            
                provide.</p>

            
            </section>


            </manualpage>
	<?xml version='1.0' encoding='UTF-8' ?>
	<!DOCTYPE manualpage SYSTEM "./style/manualpage.dtd">
	<?xml-stylesheet type="text/xsl" href="./style/manual.en.xsl"?>
	<!-- $LastChangedRevision$ -->

	<!--
	Licensed to the Apache Software Foundation (ASF) under one or more
	contributor license agreements. See the NOTICE file distributed with
	this work for additional information regarding copyright ownership.
	The ASF licenses this file to You under the Apache License, Version 2.0
	(the "License"); you may not use this file except in compliance with
	the License. You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	-->

	<manualpage metafile="invoking.xml.meta">

	<title>Starting Apache</title>

	<summary>
	<p>On Windows, Apache is normally run as a service.
	For details, see <a
	href="platform/windows.html#winsvc">Running Apache as a Service</a>.
	</p>

	<p>On Unix, the <program>httpd</program> program
	is run as a daemon that executes continuously in the
	background to handle requests. This document describes how
	to invoke <program>httpd</program>.</p>
	</summary>

	<seealso><a href="stopping.html">Stopping and Restarting</a></seealso>
	<seealso><program>httpd</program></seealso>
	<seealso><program>apachectl</program></seealso>

	<section id="startup"><title>How Apache Starts</title>

	<p>If the <directive module="mpm_common">Listen</directive>
	specified in the configuration file is default of 80 (or any other
	port below 1024), then it is necessary to have root privileges in
	order to start apache, so that it can bind to this privileged
	port. Once the server has started and performed a few preliminary
	activities such as opening its log files, it will launch several
	<em>child</em> processes which do the work of listening for and
	answering requests from clients. The main <code>httpd</code>
	process continues to run as the root user, but the child processes
	run as a less privileged user. This is controlled by the selected
	<a href="mpm.html">Multi-Processing Module</a>.</p>

	<p>The recommended method of invoking the <program>httpd</program>
	executable is to use the <program>apachectl</program> control script. This
	script sets certain environment variables that are necessary for
	<program>httpd</program> to function correctly under some operating
	systems, and then invokes the <program>httpd</program> binary.
	<program>apachectl</program> will pass through any command line
	arguments, so any <program>httpd</program> options may also be used with
	<program>apachectl</program>. You may also directly edit the
	<program>apachectl</program> script by changing the <code>HTTPD</code>
	variable near the top to specify the correct location of the
	<program>httpd</program> binary and any command-line arguments that you
	wish to be <em>always</em> present.</p>

	<p>The first thing that <program>httpd</program> does when it is
	invoked is to locate and read the <a
	href="configuring.html">configuration file</a>
	<code>httpd.conf</code>. The location of this file is set at
	compile-time, but it is possible to specify its location at run
	time using the <code>-f</code> command-line option as in</p>

	<example>/usr/local/apache2/bin/apachectl -f
	/usr/local/apache2/conf/httpd.conf</example>

	<p>If all goes well during startup, the server will detach from
	the terminal and the command prompt will return almost
	immediately. This indicates that the server is up and running.
	You can then use your browser to connect to the server and view
	the test page in the <directive
	module="core">DocumentRoot</directive> directory.</p>
	</section>

	<section id="errors"><title>Errors During Start-up</title>

	<p>If Apache suffers a fatal problem during startup, it will
	write a message describing the problem either to the console or
	to the <directive module="core">ErrorLog</directive> before
	exiting. One of the most common error messages is "<code>Unable
	to bind to Port ...</code>". This message is usually caused by
	either:</p>

	<ul>
	<li>Trying to start the server on a privileged port when not
	logged in as the root user; or</li>

	<li>Trying to start the server when there is another instance
	of Apache or some other web server already bound to the same
	Port.</li>
	</ul>

	<p>For further trouble-shooting instructions, consult the
	Apache <a href="https://cwiki.apache.org/confluence/display/httpd/FAQ">FAQ</a>.</p>
	</section>

	<section id="boot"><title>Starting at Boot-Time</title>

	<p>If you want your server to continue running after a system
	reboot, you should add a call to <program>apachectl</program> to your
	system startup files (typically <code>rc.local</code> or a file in
	an <code>rc.N</code> directory). This will start Apache as
	root. Before doing this ensure that your server is properly
	configured for security and access restrictions.</p>

	<p>The <program>apachectl</program> script is designed to act like a
	standard SysV init script; it can take the arguments
	<code>start</code>, <code>restart</code>, and <code>stop</code>
	and translate them into the appropriate signals to
	<program>httpd</program>. So you can often simply link
	<program>apachectl</program> into the appropriate init directory. But be
	sure to check the exact requirements of your system.</p>
	</section>

	<section id="info"><title>Additional Information</title>

	<p>Additional information about the command-line options of <program>
	httpd</program> and <program>apachectl</program> as well as other support
	programs included with the server is available on the
	<a href="programs/">Server and Supporting Programs</a> page.
	There is also documentation on all the <a
	href="mod/">modules</a> included with the Apache distribution
	and the <a href="mod/directives.html">directives</a> that they
	provide.</p>
	</section>

	</manualpage>