8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<?xml version="1.0"?>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<!DOCTYPE modulesynopsis SYSTEM "/style/modulesynopsis.dtd">

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<?xml-stylesheet type="text/xsl" href="/style/manual.en.xsl"?>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<modulesynopsis metafile="mpm_common.xml.meta">

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<name>mpm_common</name>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<description>A collection of directives that are implemented by

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallynmore than one multi-processing module (MPM)</description>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<status>MPM</status>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<directivesynopsis>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<name>AcceptMutex</name>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<description>Method that Apache uses to serialize multiple children

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallynaccepting requests on network sockets</description>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<syntax>AcceptMutex Default|<var>method</var></syntax>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<default>AcceptMutex Default</default>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<contextlist><context>server config</context></contextlist>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<modulelist><module>leader</module><module>perchild</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<module>prefork</module><module>threadpool</module><module>worker</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn</modulelist>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<usage>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>The <directive>AcceptMutex</directive> directives sets the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn method that Apache uses to serialize multiple children accepting

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn requests on network sockets. Prior to Apache 2.0, the method was

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn selectable only at compile time. The optimal method to use is

9ec45e7faa3648a36cb01aed9e230bd49b450fe0Serge Hallyn highly architecture and platform dependent. For further details,

9ec45e7faa3648a36cb01aed9e230bd49b450fe0Serge Hallyn see the <a href="/misc/perf-tuning.html">performance tuning</a>

9ec45e7faa3648a36cb01aed9e230bd49b450fe0Serge Hallyn documentation.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>If this directive is set to <code>Default</code>, then the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn compile-time selected default will be used. Other possible

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn methods are listed below. Note that not all methods are

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn available on all platforms. If a method is specified which is

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn not available, a message will be written to the error log

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn listing the available methods.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dl>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dt><code>flock</code></dt>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dd>uses the <code>flock(2)</code> system call to lock the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn file defined by the <directive module="mpm_common"

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn >LockFile</directive> directive.</dd>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dt><code>fcntl</code></dt>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dd>uses the <code>fcntl(2)</code> system call to lock the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn file defined by the <directive module="mpm_common"

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn >LockFile</directive> directive.</dd>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dt><code>posixsem</code></dt>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dd>uses POSIX compatible semaphores to implement the mutex.</dd>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dt><code>pthread</code></dt>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dd>uses POSIX mutexes as implemented by the POSIX Threads

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn (PThreads) specification.</dd>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dt><code>sysvsem</code></dt>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dd>uses SySV-style semaphores to implement the mutex.</dd>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn </dl>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>If you want to find out the compile time chosen default

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn for your system, you may set your <directive module="core"

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn >LogLevel</directive> to <code>debug</code>. Then the default <directive

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn >AcceptMutex</directive> will be written into the <directive

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn module="core">ErrorLog</directive>.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <note type="warning"><title>Warning</title>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>On most systems, when the <code>pthread</code> option

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn is selected, if a child process terminates abnormally

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn while holding the <code>AcceptCntl</code> mutex the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn server will stop responding to requests. When this

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn occurs, the server will require a manual restart to

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn recover.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>Solaris is a notable exception as it provides a

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn mechanism, used by Apache, which usually allows the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn mutex to be recovered after a child process terminates

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn abnormally while holding a mutex.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>If your system implements the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <code>pthread_mutexattr_setrobust_np()</code> function,

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn you may be able to use the <code>pthread</code> option safely.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn </note>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn</usage>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn</directivesynopsis>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<directivesynopsis>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<name>CoreDumpDirectory</name>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<description>Directory where Apache attempts to

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallynswitch before dumping core</description>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<syntax>CoreDumpDirectory <var>directory</var></syntax>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<default>See usage for the default setting</default>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<contextlist><context>server config</context></contextlist>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<modulelist><module>beos</module><module>leader</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<module>mpm_winnt</module><module>perchild</module><module>prefork</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<module>threadpool</module><module>worker</module></modulelist>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<usage>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>This controls the directory to which Apache attempts to

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn switch before dumping core. The default is in the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <directive module="core">ServerRoot</directive> directory, however

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn since this should not be writable by the user the server runs

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn as, core dumps won't normally get written. If you want a core

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn dump for debugging, you can use this directive to place it in a

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn different location.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <note><title>Core Dumps on Linux</title>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>If Apache starts as root and switches to another user, the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn Linux kernel <em>disables</em> core dumps even if the directory is

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn writable for the process. Apache (2.0.46 and later) reenables core dumps

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn on Linux 2.4 and beyond, but only if you explicitly configure a <directive

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn >CoreDumpDirectory</directive>.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn </note>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn</usage>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn</directivesynopsis>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<directivesynopsis>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<name>Group</name>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<description>Group under which the server will answer

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallynrequests</description>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<syntax>Group <var>unix-group</var></syntax>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<default>Group #-1</default>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<contextlist><context>server config</context></contextlist>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<modulelist><module>beos</module><module>leader</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<module>mpmt_os2</module><module>perchild</module><module>prefork</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<module>threadpool</module><module>worker</module></modulelist>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<compatibility>Only valid in global server config since Apache

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn2.0</compatibility>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<usage>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>The <directive>Group</directive> directive sets the group under

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn which the server will answer requests. In order to use this

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn directive, the server must be run initially as <code>root</code>. If

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn you start the server as a non-root user, it will fail to change to the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn specified group, and will instead continue to run as the group of the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn original user. <var>Unix-group</var> is one of:</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dl>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dt>A group name</dt>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dd>Refers to the given group by name.</dd>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dt><code>#</code> followed by a group number.</dt>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <dd>Refers to a group by its number.</dd>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn </dl>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <example><title>Example</title>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn Group www-group

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn </example>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>It is recommended that you set up a new group specifically for

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn running the server. Some admins use user <code>nobody</code>,

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn but this is not always possible or desirable.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <note type="warning"><title>Security</title>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>Don't set <directive>Group</directive> (or <directive

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn module="mpm_common">User</directive>) to <code>root</code> unless

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn you know exactly what you are doing, and what the dangers are.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn </note>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>Special note: Use of this directive in <directive module="core"

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn type="section">VirtualHost</directive> is no longer supported. To

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn configure your server for <a href="mod_suexec.html">suexec</a> use

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <directive module="mod_suexec">SuexecUserGroup</directive>.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <note><title>Note</title>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>Although the <directive>Group</directive> directive is present

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn in the <module>beos</module> and <module>mpmt_os2</module> MPMs,

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn it is actually a no-op there and only exists for compatibility

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn reasons.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn </note>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn</usage>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn</directivesynopsis>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<directivesynopsis>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<name>PidFile</name>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<description>File where the server records the process ID

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallynof the daemon</description>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<syntax>PidFile <var>filename</var></syntax>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<default>PidFile logs/httpd.pid</default>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<contextlist><context>server config</context></contextlist>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<modulelist><module>beos</module><module>leader</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<module>mpm_winnt</module><module>mpmt_os2</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<module>perchild</module><module>prefork</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<module>threadpool</module><module>worker</module></modulelist>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<usage>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>The <directive>PidFile</directive> directive sets the file to

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn which the server records the process id of the daemon. If the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn filename is not absolute then it is assumed to be relative to the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <directive module="core">ServerRoot</directive>.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <example><title>Example</title>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn PidFile /var/run/apache.pid

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn </example>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>It is often useful to be able to send the server a signal,

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn so that it closes and then re-opens its <directive

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn module="core">ErrorLog</directive> and <directive

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn module="mod_log_config">TransferLog</directive>, and

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn re-reads its configuration files. This is done by sending a

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn SIGHUP (kill -1) signal to the process id listed in the

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <directive>PidFile</directive>.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>The <directive>PidFile</directive> is subject to the same

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn warnings about log file placement and <a

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn href="/misc/security_tips.html#serverroot">security</a>.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <note><title>Note</title>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn <p>As of Apache 2 it is recommended to use only the <a

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn href="/programs/apachectl.html">apachectl</a> script for

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn (re-)starting or stopping the server.</p>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn </note>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn</usage>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn</directivesynopsis>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<directivesynopsis>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<name>Listen</name>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<description>IP addresses and ports that the server

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallynlistens to</description>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<syntax>Listen [<var>IP-address</var>:]<var>portnumber</var></syntax>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<contextlist><context>server config</context></contextlist>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<modulelist><module>beos</module><module>leader</module>

8aa1044fd83c407e38c66a1ff46a9edfe02d7c78Serge Hallyn<module>mpm_netware</module><module>mpm_winnt</module>

<module>mpmt_os2</module><module>perchild</module>

<module>prefork</module><module>threadpool</module><module>worker</module>

</modulelist>

<compatibility>Required directive since Apache 2.0</compatibility>

<usage>

<p>The <directive>Listen</directive> directive instructs Apache to

listen to only specific IP addresses or ports; by default it

responds to requests on all IP interfaces. <directive>Listen</directive>

is now a required directive. If it is not in the config file, the

server will fail to start. This is a change from previous versions

of Apache.</p>

<p>The <directive>Listen</directive> directive tells the server to

accept incoming requests on the specified port or address-and-port

combination. If only a port number is specified, the server listens to

the given port on all interfaces. If an IP address is given as well

as a port, the server will listen on the given port and

interface.</p>

<p>Multiple <directive>Listen</directive> directives may be used to

specify a number of addresses and ports to listen to. The server will

respond to requests from any of the listed addresses and ports.</p>

<p>For example, to make the server accept connections on both

port 80 and port 8000, use:</p>

<example>

Listen 80<br />

Listen 8000

</example>

<p>To make the server accept connections on two specified

interfaces and port numbers, use </p>

<example>

Listen 192.170.2.1:80<br />

Listen 192.170.2.5:8000

</example>

<p>IPv6 addresses must be surrounded in square brackets, as in the

following example:</p>

<example>

Listen [fe80::a00:20ff:fea7:ccea]:80

</example>

</usage>

<seealso><a href="/dns-caveats.html">DNS Issues</a></seealso>

<seealso><a href="/bind.html">Setting which addresses and ports Apache

uses</a></seealso>

</directivesynopsis>

<directivesynopsis>

<name>ListenBackLog</name>

<description>Maximum length of the queue of pending connections</description>

<syntax>ListenBacklog <var>backlog</var></syntax>

<default>ListenBacklog 511</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>beos</module><module>leader</module>

<module>mpm_netware</module><module>mpm_winnt</module>

<module>mpmt_os2</module><module>perchild</module><module>prefork</module>

<module>threadpool</module><module>worker</module></modulelist>

<usage>

<p>The maximum length of the queue of pending connections.

Generally no tuning is needed or desired, however on some

systems it is desirable to increase this when under a TCP SYN

flood attack. See the backlog parameter to the

<code>listen(2)</code> system call.</p>

<p>This will often be limited to a smaller number by the

operating system. This varies from OS to OS. Also note that

many OSes do not use exactly what is specified as the backlog,

but use a number based on (but normally larger than) what is

set.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>LockFile</name>

<description>Location of the accept serialization lock file</description>

<syntax>LockFile <var>filename</var></syntax>

<default>LockFile logs/accept.lock</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>leader</module><module>perchild</module>

<module>prefork</module><module>threadpool</module><module>worker</module>

</modulelist>

<usage>

<p>The <directive>LockFile</directive> directive sets the path to

the lockfile used when Apache is used with an <directive

module="mpm_common">AcceptMutex</directive> value of either

<code>fcntl</code> or <code>flock</code>. This directive should

normally be left at its default value. The main reason for changing

it is if the <code>logs</code> directory is NFS mounted, since

<strong>the lockfile must be stored on a local disk</strong>. The PID

of the main server process is automatically appended to the

filename.</p>

<note type="warning"><title>Security</title>

<p>It is best to <em>avoid</em> putting this file in a world writable

directory such as <code>/var/tmp</code> because someone could create

a denial of service attack and prevent the server from starting by

creating a lockfile with the same name as the one the server will try

to create.</p>

</note>

</usage>

<seealso><directive module="mpm_common">AcceptMutex</directive></seealso>

</directivesynopsis>

<directivesynopsis>

<name>MaxClients</name>

<description>Maximum number of child processes that will be created

to serve requests</description>

<syntax>MaxClients <var>number</var></syntax>

<default>See usage for details</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>beos</module><module>leader</module>

<module>prefork</module><module>threadpool</module><module>worker</module>

</modulelist>

<usage>

<p>The <directive>MaxClients</directive> directive sets the limit

on the number of simultaneous requests that will be served. Any

connection attempts over the <directive>MaxClients</directive>

limit will normally be queued, up to a number based on the

<directive module="mpm_common">ListenBacklog</directive>

directive. Once a child process is freed at the end of a different

request, the connection will then be serviced.</p>

<p>For non-threaded servers (<em>i.e.</em>, <module>prefork</module>),

<directive>MaxClients</directive> translates into the maximum

number of child processes that will be launched to serve requests.

The default value is <code>256</code>; to increase it, you must also raise

<directive module="mpm_common">ServerLimit</directive>.</p>

<p>For threaded and hybrid servers (<em>e.g.</em> <module>beos</module>

or <module>worker</module>) <directive>MaxClients</directive> restricts

the total number of threads that will be available to serve clients.

The default value for <module>beos</module> is <code>50</code>. For

hybrid MPMs the default value is <code>16</code> (<directive

module="mpm_common">ServerLimit</directive>) multiplied by the value of

<code>25</code> (<directive module="mpm_common"

>ThreadsPerChild</directive>). Therefore, to increase <directive

>MaxClients</directive> to a value that requires more than 16 processes,

you must also raise <directive module="mpm_common"

>ServerLimit</directive>.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>MaxMemFree</name>

<description>Maximum amount of memory that the main allocator is allowed

to hold without calling <code>free()</code></description>

<syntax>MaxMemFree <var>KBytes</var></syntax>

<default>MaxMemFree 0</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>beos</module><module>leader</module>

<module>mpm_netware</module><module>prefork</module>

<module>threadpool</module><module>worker</module><module>mpm_winnt</module></modulelist>

<usage>

<p>The <directive>MaxMemFree</directive> directive sets the

maximum number of free Kbytes that the main allocator is allowed

to hold without calling <code>free()</code>. When not set, or when set

to zero, the threshold will be set to unlimited.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>MaxRequestsPerChild</name>

<description>Limit on the number of requests that an individual child server

will handle during its life</description>

<syntax>MaxRequestsPerChild <var>number</var></syntax>

<default>MaxRequestsPerChild 10000</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>leader</module><module>mpm_netware</module>

<module>mpm_winnt</module><module>mpmt_os2</module>

<module>perchild</module><module>prefork</module>

<module>threadpool</module><module>worker</module></modulelist>

<usage>

<p>The <directive>MaxRequestsPerChild</directive> directive sets

the limit on the number of requests that an individual child

server process will handle. After

<directive>MaxRequestsPerChild</directive> requests, the child

process will die. If <directive>MaxRequestsPerChild</directive> is

<code>0</code>, then the process will never expire.</p>

<note><title>Different default values</title>

<p>The default value for <module>mpm_netware</module> and

<module>mpm_winnt</module> is <code>0</code>.</p>

</note>

<p>Setting <directive>MaxRequestsPerChild</directive> to a

non-zero limit has two beneficial effects:</p>

<ul>

<li>it limits the amount of memory that process can consume

by (accidental) memory leakage;</li>

<li>by giving processes a finite lifetime, it helps reduce

the number of processes when the server load reduces.</li>

</ul>

<note><title>Note</title>

<p>For <directive module="core">KeepAlive</directive> requests, only

the first request is counted towards this limit. In effect, it

changes the behavior to limit the number of <em>connections</em> per

child.</p>

</note>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>MaxSpareThreads</name>

<description>Maximum number of idle threads</description>

<syntax>MaxSpareThreads <var>number</var></syntax>

<default>See usage for details</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>beos</module><module>leader</module>

<module>mpm_netware</module><module>mpmt_os2</module>

<module>perchild</module><module>threadpool</module><module>worker</module>

</modulelist>

<usage>

<p>Maximum number of idle threads. Different MPMs deal with this

directive differently.</p>

<p>For <module>perchild</module> the default is

<code>MaxSpareThreads 10</code>. This MPM monitors the number of

idle threads on a per-child basis. If there are too many idle

threads in that child, the server will begin to kill threads

within that child.</p>

<p>For <module>worker</module>, <module>leader</module> and <module

>threadpool</module> the default is <code>MaxSpareThreads 250</code>.

These MPMs deal with idle threads on a server-wide basis. If there

are too many idle threads in the server then child processes are

killed until the number of idle threads is less than this number.</p>

<p>For <module>mpm_netware</module> the default is

<code>MaxSpareThreads 100</code>. Since this MPM runs a

single-process, the spare thread count is also server-wide.</p>

<p><module>beos</module> and <module>mpmt_os2</module> work

similar to <module>mpm_netware</module>. The default for

<module>beos</module> is <code>MaxSpareThreads 50</code>. For

<module>mpmt_os2</module> the default value is <code>10</code>.</p>

<note><title>Restrictions</title>

<p>The range of the <directive>MaxSpareThreads</directive> value

is restricted. Apache will correct the given value automatically

according to the following rules:</p>

<ul>

<li><module>perchild</module> requires <directive

>MaxSpareThreads</directive> to be less or equal than <directive

module="mpm_common">ThreadLimit</directive>.</li>

<li><module>mpm_netware</module> wants the value to be greater than

<directive module="mpm_common">MinSpareThreads</directive>.</li>

<li>For <module>leader</module>, <module>threadpool</module> and

<module>worker</module> the value must be greater or equal than

the sum of <directive module="mpm_common">MinSpareThreads</directive>

and <directive module="mpm_common">ThreadsPerChild</directive>.</li>

</ul>

</note>

</usage>

<seealso><directive module="mpm_common">MinSpareThreads</directive></seealso>

<seealso><directive module="mpm_common">StartServers</directive></seealso>

</directivesynopsis>

<directivesynopsis>

<name>MinSpareThreads</name>

<description>Minimum number of idle threads available to handle request

spikes</description>

<syntax>MinSpareThreads <var>number</var></syntax>

<default>See usage for details</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>beos</module><module>leader</module>

<module>mpm_netware</module><module>mpmt_os2</module>

<module>perchild</module><module>threadpool</module><module>worker</module>

</modulelist>

<usage>

<p>Minimum number of idle threads to handle request spikes.

Different MPMs deal with this directive

differently.</p>

<p><module>perchild</module> uses a default of

<code>MinSpareThreads 5</code> and monitors the number of idle

threads on a per-child basis. If there aren't enough idle threads

in that child, the server will begin to create new threads within

that child. Thus, if you set <directive module="perchild"

>NumServers</directive> to <code>10</code> and a <directive

>MinSpareThreads</directive> value of <code>5</code>, you'll have

at least 50 idle threads on your system.</p>

<p><module>worker</module>, <module>leader</module> and

<module>threadpool</module> use a default of <code>MinSpareThreads

75</code> and deal with idle threads on a server-wide basis. If

there aren't enough idle threads in the server then child

processes are created until the number of idle threads is greater

than number.</p>

<p><module>mpm_netware</module> uses a default of

<code>MinSpareThreads 10</code> and, since it is a single-process

MPM, tracks this on a server-wide bases.</p>

<p><module>beos</module> and <module>mpmt_os2</module> work

similar to <module>mpm_netware</module>. The default for

<module>beos</module> is <code>MinSpareThreads 1</code>. For

<module>mpmt_os2</module> the default value is <code>5</code>.</p>

</usage>

<seealso><directive module="mpm_common">MaxSpareThreads</directive></seealso>

<seealso><directive module="mpm_common">StartServers</directive></seealso>

</directivesynopsis>

<directivesynopsis>

<name>ScoreBoardFile</name>

<description>Location of the file used to store coordination data for

the child processes</description>

<syntax>ScoreBoardFile <var>file-path</var></syntax>

<default>ScoreBoardFile logs/apache_status</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>beos</module><module>leader</module>

<module>mpm_winnt</module><module>perchild</module><module>prefork</module>

<module>threadpool</module><module>worker</module></modulelist>

<usage>

<p>Apache uses a scoreboard to communicate between its parent

and child processes. Some architectures require a file to facilitate

this communication. If the file is left unspecified, Apache first

attempts to create the scoreboard entirely in memory (using anonymous

shared memory) and, failing that, will attempt to create the file on

disk (using file-based shared memory). Specifying this directive causes

Apache to always create the file on the disk.</p>

<example><title>Example</title>

ScoreBoardFile /var/run/apache_status

</example>

<p>File-based shared memory is useful for third-party applications

that require direct access to the scoreboard.</p>

<p>If you use a <directive>ScoreBoardFile</directive> then

you may see improved speed by placing it on a RAM disk. But be

careful that you heed the same warnings about log file placement

and <a href="/misc/security_tips.html">security</a>.</p>

</usage>

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

Apache</a></seealso>

</directivesynopsis>

<directivesynopsis>

<name>SendBufferSize</name>

<description>TCP buffer size</description>

<syntax>SendBufferSize <var>bytes</var></syntax>

<default>SendBufferSize 0</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>beos</module><module>leader</module>

<module>mpm_netware</module><module>mpm_winnt</module>

<module>mpmt_os2</module><module>perchild</module><module>prefork</module>

<module>threadpool</module><module>worker</module></modulelist>

<usage>

<p>The server will set the TCP buffer size to the number of bytes

specified. Very useful to increase past standard OS defaults on

high speed high latency (<em>i.e.</em>, 100ms or so, such as

transcontinental fast pipes).</p>

<p>If set to the value of <code>0</code>, the server will use the

OS deault.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>ServerLimit</name>

<description>Upper limit on configurable number of processes</description>

<syntax>ServerLimit <var>number</var></syntax>

<default>See usage for details</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>leader</module><module>perchild</module>

<module>prefork</module><module>threadpool</module><module>worker</module>

</modulelist>

<usage>

<p>For the <module>prefork</module> MPM, this directive sets the

maximum configured value for <directive

module="mpm_common">MaxClients</directive> for the lifetime of the

Apache process. For the <module>worker</module> MPM, this directive

in combination with <directive

module="mpm_common">ThreadLimit</directive> sets

the maximum configured value for <directive

module="mpm_common">MaxClients</directive> for the lifetime of the

Apache process. Any attempts to change this directive during a

restart will be ignored, but <directive

module="mpm_common">MaxClients</directive> can be modified during

a restart.</p>

<p>Special care must be taken when using this directive. If

<directive>ServerLimit</directive> is set to a value much higher

than necessary, extra, unused shared memory will be allocated. If

both <directive>ServerLimit</directive> and <directive

module="mpm_common">MaxClients</directive> are set to values

higher than the system can handle, Apache may not start or the

system may become unstable.</p>

<p>With the <module>prefork</module> MPM, use this directive only

if you need to set <directive

module="mpm_common">MaxClients</directive> higher than 256 (default).

Do not set the value of this directive any higher than what you

might want to set <directive

module="mpm_common">MaxClients</directive> to.</p>

<p>With <module>worker</module>, <module>leader</module> and

<module>threadpool</module> use this directive only

if your <directive module="mpm_common">MaxClients</directive> and

<directive module="mpm_common">ThreadsPerChild</directive>

settings require more than 16 server processes (default). Do not set

the value of this directive any higher than the number of server

processes required by what you may want for <directive

module="mpm_common">MaxClients </directive> and <directive

module="mpm_common">ThreadsPerChild</directive>.</p>

<p>With the <module>perchild</module> MPM, use this directive only

if you need to set <directive

module="perchild">NumServers</directive> higher than 8 (default).</p>

<note><title>Note</title>

<p>There is a hard limit of <code>ServerLimit 20000</code> compiled

into the server. This is intended to avoid nasty effects caused by

typos.</p>

</note>

</usage>

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

</directivesynopsis>

<directivesynopsis>

<name>StartServers</name>

<description>Number of child server processes created at startup</description>

<syntax>StartServers <var>number</var></syntax>

<default>See usage for details</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>leader</module><module>mpmt_os2</module>

<module>prefork</module><module>threadpool</module><module>worker</module>

</modulelist>

<usage>

<p>The <directive>StartServers</directive> directive sets the

number of child server processes created on startup. As the number

of processes is dynamically controlled depending on the load,

there is usually little reason to adjust this parameter.</p>

<p>The default value differs from MPM to MPM. For

<module>leader</module>, <module>threadpool</module> and

<module>worker</module> the default is <code>StartServers 3</code>.

For <module>prefork</module> defaults to <code>5</code> and for

<module>mpmt_os2</module> to <code>2</code>.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>StartThreads</name>

<description>Number of threads created on startup</description>

<syntax>StartThreads <var>number</var></syntax>

<default>See usage for details</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>beos</module><module>mpm_netware</module>

<module>perchild</module></modulelist>

<usage>

<p>Number of threads created on startup. As the

number of threads is dynamically controlled depending on the

load, there is usually little reason to adjust this

parameter.</p>

<p>For <module>perchild</module> the default is <code>StartThreads

5</code> and this directive tracks the number of threads per

process at startup.</p>

<p>For <module>mpm_netware</module> the default is

<code>StartThreads 50</code> and, since there is only a single

process, this is the total number of threads created at startup to

serve requests.</p>

<p>For <module>beos</module> the default is <code>StartThreads

10</code>. It also reflects the total number of threads created

at startup to serve requests.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>ThreadLimit</name>

<description>Sets the upper limit on the configurable number of threads

per child process</description>

<syntax>ThreadLimit <var>number</var></syntax>

<default>See usage for details</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>leader</module><module>mpm_winnt</module>

<module>perchild</module><module>threadpool</module><module>worker</module>

</modulelist>

<compatibility>Available for <module>mpm_winnt</module> in Apache 2.0.41

and later</compatibility>

<usage>

<p>This directive sets the maximum configured value for <directive

module="mpm_common">ThreadsPerChild</directive> for the lifetime

of the Apache process. Any attempts to change this directive

during a restart will be ignored, but <directive

module="mpm_common">ThreadsPerChild</directive> can be modified

during a restart up to the value of this directive.</p>

<p>Special care must be taken when using this directive. If

<directive>ThreadLimit</directive> is set to a value much higher

than <directive module="mpm_common">ThreadsPerChild</directive>,

extra unused shared memory will be allocated. If both

<directive>ThreadLimit</directive> and <directive

module="mpm_common">ThreadsPerChild</directive> are set to values

higher than the system can handle, Apache may not start or the

system may become unstable. Do not set the value of this directive

any higher than your greatest predicted setting of <directive

module="mpm_common">ThreadsPerChild</directive> for the

current run of Apache.</p>

<p>The default value for <directive>ThreadLimit</directive> is

<code>1920</code> when used with <module>mpm_winnt</module> and

<code>64</code> when used with the others.</p>

<note><title>Note</title>

<p>There is a hard limit of <code>ThreadLimit 20000</code> (or

<code>ThreadLimit 15000</code> with <module>mpm_winnt</module>)

compiled into the server. This is intended to avoid nasty effects

caused by typos.</p>

</note>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>ThreadsPerChild</name>

<description>Number of threads created by each child process</description>

<syntax>ThreadsPerChild <var>number</var></syntax>

<default>See usage for details</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>leader</module><module>mpm_winnt</module>

<module>threadpool</module><module>worker</module></modulelist>

<usage>

<p>This directive sets the number of threads created by each

child process. The child creates these threads at startup and

never creates more. If using an MPM like <module>mpm_winnt</module>,

where there is only one child process, this number should be high

enough to handle the entire load of the server. If using an MPM

like <module>worker</module>, where there are multiple child processes,

the <em>total</em> number of threads should be high enough to handle

the common load on the server.</p>

<p>The default value for <directive>ThreadsPerChild</directive> is

<code>64</code> when used with <module>mpm_winnt</module> and

<code>25</code> when used with the others.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>User</name>

<description>The userid under which the server will answer

requests</description>

<syntax>User <var>unix-userid</var></syntax>

<default>User #-1</default>

<contextlist><context>server config</context></contextlist>

<modulelist><module>leader</module><module>perchild</module>

<module>prefork</module><module>threadpool</module><module>worker</module>

</modulelist>

<compatibility>Only valid in global server config since Apache

2.0</compatibility>

<usage>

<p>The <directive>User</directive> directive sets the user ID as

which the server will answer requests. In order to use this

directive, the server must be run initially as <code>root</code>.

If you start the server as a non-root user, it will fail to change

to the lesser privileged user, and will instead continue to run as

that original user. If you do start the server as <code>root</code>,

then it is normal for the parent process to remain running as root.

<var>Unix-userid</var> is one of:</p>

<dl>

<dt>A username</dt>

<dd>Refers to the given user by name.</dd>

<dt># followed by a user number.</dt>

<dd>Refers to a user by its number.</dd>

</dl>

<p>The user should have no privileges that result in it being

able to access files that are not intended to be visible to the

outside world, and similarly, the user should not be able to

execute code that is not meant for HTTP requests. It is

recommended that you set up a new user and group specifically for

running the server. Some admins use user <code>nobody</code>, but

this is not always desirable, since the <code>nobody</code> user

can have other uses on the system.</p>

<note type="warning"><title>Security</title>

<p>Don't set <directive>User</directive> (or <directive

module="mpm_common">Group</directive>) to <code>root</code> unless

you know exactly what you are doing, and what the dangers are.</p>

</note>

<p>With the <module>perchild</module> MPM, which is intended to

server virtual hosts run under different user IDs, the

<directive>User</directive> directive defines the user ID for the

main server and the fallback for <directive type="section"

module="core">VirtualHost</directive> sections without an

<directive module="perchild">AssignUserID</directive> directive.</p>

<p>Special note: Use of this directive in <directive module="core"

type="section">VirtualHost</directive> is no longer supported. To

configure your server for <a href="/suexec.html">suexec</a> use

<directive module="mod_suexec">SuexecUserGroup</directive>.</p>

<note><title>Note</title>

<p>Although the <directive>User</directive> directive is present

in the <module>beos</module> and <module>mpmt_os2</module> MPMs,

it is actually a no-op there and only exists for compatibility

reasons.</p>

</note>

</usage>

</directivesynopsis>

</modulesynopsis>