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<title>Configuration Files</title>

<summary>

<p>This document describes the files used to configure Apache HTTP

Server.</p>

</summary>

<section id="main">

<title>Main Configuration Files</title>

<related>

<modulelist>

<module>mod_mime</module>

</modulelist>

<directivelist>

<directive module="core" type="section">IfDefine</directive>

<directive module="core">Include</directive>

<directive module="mod_mime">TypesConfig</directive>

</directivelist>

</related>

<p>Apache HTTP Server is configured by placing <a

href="mod/directives.html">directives</a> in plain text

configuration files. The main configuration file is usually called

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

compile-time, but may be overridden with the <code>-f</code>

command line flag. In addition, other configuration files may be

added using the <directive module="core">Include</directive>

directive, and wildcards can be used to include many configuration

files. Any directive may be placed in any of these configuration

files. Changes to the main configuration files are only

recognized by httpd when it is started or restarted.</p>

<p>The server also reads a file containing mime document types;

the filename is set by the <directive

module="mod_mime">TypesConfig</directive> directive,

and is <code>mime.types</code> by default.</p>

</section>

<section id="syntax">

<title>Syntax of the Configuration Files</title>

<p>httpd configuration files contain one directive per line.

The backslash "\" may be used as the last character on a line

to indicate that the directive continues onto the next line.

There must be no other characters or white space between the

backslash and the end of the line.</p>

<p>Directives in the configuration files are case-insensitive,

but arguments to directives are often case sensitive. Lines

that begin with the hash character "#" are considered

comments, and are ignored. Comments may <strong>not</strong> be

included on a line after a configuration directive. Blank lines

and white space occurring before a directive are ignored, so

you may indent directives for clarity.</p>

<p>The values of variables defined with the <directive

module="core">Define</directive> of or shell environment variables can

be used in configuration file lines using the syntax <code>${VAR}</code>.

If "VAR" is the name of a valid variable, the value of that variable is

substituted into that spot in the configuration file line, and processing

continues as if that text were found directly in the configuration file.

Variables defined with <directive module="core">Define</directive> take

precedence over shell environment variables.

If the "VAR" variable is not found, the characters <code>${VAR}</code>

are left unchanged, and a warning is logged.

Variable names may not contain colon ":" characters, to avoid clashes with

<directive module="mod_rewrite">RewriteMap</directive>'s syntax.</p>

<p>Only shell environment variables defined before the server is started

can be used in expansions. Environment variables defined in the

configuration file itself, for example with <directive

module="mod_env">SetEnv</directive>, take effect too late to be used for

expansions in the configuration file.</p>

<p>The maximum length of a line in normal configuration files, after

variable substitution and joining any continued lines, is approximately

16 MiB. In <a href="configuring.xml#htaccess">.htaccess files</a>, the

maximum length is 8190 characters.</p>

<p>You can check your configuration files for syntax errors

without starting the server by using <code>apachectl

configtest</code> or the <code>-t</code> command line

option.</p>

<p>You can use <module>mod_info</module>'s <code>-DDUMP_CONFIG</code> to

dump the configuration with all included files and environment

variables resolved and all comments and non-matching

<directive module="core" type="section">IfDefine</directive> and

<directive module="core" type="section">IfModule</directive> sections

removed.</p>

</section>

<section id="modules">

<title>Modules</title>

<related>

<modulelist>

<module>mod_so</module>

</modulelist>

<directivelist>

<directive module="core" type="section">IfModule</directive>

<directive module="mod_so">LoadModule</directive>

</directivelist>

</related>

<p>httpd is a modular server. This implies that only the most

basic functionality is included in the core server. Extended

features are available through <a

href="mod/">modules</a> which can be loaded

into httpd. By default, a <a

href="mod/module-dict.html#Status">base</a> set of modules is

included in the server at compile-time. If the server is

compiled to use <a href="dso.html">dynamically loaded</a>

modules, then modules can be compiled separately and added at

any time using the <directive module="mod_so">LoadModule</directive>

directive.

Otherwise, httpd must be recompiled to add or remove modules.

Configuration directives may be included conditional on a

presence of a particular module by enclosing them in an <directive

module="core" type="section">IfModule</directive> block. However,

<directive type="section">IfModule</directive> blocks are not

required, and in some cases may mask the fact that you're missing an

important module.</p>

<p>To see which modules are currently compiled into the server,

you can use the <code>-l</code> command line option. You can also

see what modules are loaded dynamically using the <code>-M</code>

command line option.</p>

</section>

<section id="scope">

<title>Scope of Directives</title>

<related>

<directivelist>

<directive module="core" type="section">Directory</directive>

<directive module="core" type="section">DirectoryMatch</directive>

<directive module="core" type="section">Files</directive>

<directive module="core" type="section">FilesMatch</directive>

<directive module="core" type="section">Location</directive>

<directive module="core" type="section">LocationMatch</directive>

<directive module="core" type="section">VirtualHost</directive>

</directivelist>

</related>

<p>Directives placed in the main configuration files apply to

the entire server. If you wish to change the configuration for

only a part of the server, you can scope your directives by

placing them in <directive module="core"

type="section">Directory</directive>, <directive module="core"

type="section">DirectoryMatch</directive>, <directive module="core"

type="section">Files</directive>, <directive module="core"

type="section">FilesMatch</directive>, <directive module="core"

type="section">Location</directive>, and <directive module="core"

type="section">LocationMatch</directive>

sections. These sections limit the application of the

directives which they enclose to particular filesystem

locations or URLs. They can also be nested, allowing for very

fine grained configuration.</p>

<p>httpd has the capability to serve many different websites

simultaneously. This is called <a href="vhosts/">Virtual

Hosting</a>. Directives can also be scoped by placing them

inside <directive module="core" type="section">VirtualHost</directive>

sections, so that they will only apply to requests for a

particular website.</p>

<p>Although most directives can be placed in any of these

sections, some directives do not make sense in some contexts.

For example, directives controlling process creation can only

be placed in the main server context. To find which directives

can be placed in which sections, check the <a

href="mod/directive-dict.html#Context">Context</a> of the

directive. For further information, we provide details on <a

href="sections.html">How Directory, Location and Files sections

work</a>.</p>

</section>

<section id="htaccess">

<title>.htaccess Files</title>

<related>

<directivelist>

<directive module="core">AccessFileName</directive>

<directive module="core">AllowOverride</directive>

</directivelist>

</related>

<p>httpd allows for decentralized management of configuration

via special files placed inside the web tree. The special files

are usually called <code>.htaccess</code>, but any name can be

specified in the <directive module="core">AccessFileName</directive>

directive. Directives placed in <code>.htaccess</code> files

apply to the directory where you place the file, and all

sub-directories. The <code>.htaccess</code> files follow the

same syntax as the main configuration files. Since

<code>.htaccess</code> files are read on every request, changes

made in these files take immediate effect.</p>

<p>To find which directives can be placed in

<code>.htaccess</code> files, check the <a

href="mod/directive-dict.html#Context">Context</a> of the

directive. The server administrator further controls what

directives may be placed in <code>.htaccess</code> files by

configuring the <directive module="core">AllowOverride</directive>

directive in the main configuration files.</p>

<p>For more information on <code>.htaccess</code> files, see

the <a href="howto/htaccess.html">.htaccess tutorial</a>.</p>

</section>

</manualpage>