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23 <manualpage metafile="configuring.xml.meta">
25 <title>Configuration Files</title>
28 <p>This document describes the files used to configure Apache HTTP
33 <title>Main Configuration Files</title>
36 <module>mod_mime</module>
39 <directive module="core" type="section">IfDefine</directive>
40 <directive module="core">Include</directive>
41 <directive module="mod_mime">TypesConfig</directive>
45 <p>Apache HTTP Server is configured by placing <a
46 href="mod/directives.html">directives</a> in plain text
47 configuration files. The main configuration file is usually called
48 <code>httpd.conf</code>. The location of this file is set at
49 compile-time, but may be overridden with the <code>-f</code>
50 command line flag. In addition, other configuration files may be
51 added using the <directive module="core">Include</directive>
52 directive, and wildcards can be used to include many configuration
53 files. Any directive may be placed in any of these configuration
54 files. Changes to the main configuration files are only
55 recognized by httpd when it is started or restarted.</p>
57 <p>The server also reads a file containing mime document types;
58 the filename is set by the <directive
59 module="mod_mime">TypesConfig</directive> directive,
60 and is <code>mime.types</code> by default.</p>
64 <title>Syntax of the Configuration Files</title>
66 <p>httpd configuration files contain one directive per line.
67 The backslash "\" may be used as the last character on a line
68 to indicate that the directive continues onto the next line.
69 There must be no other characters or white space between the
70 backslash and the end of the line.</p>
72 <p>Directives in the configuration files are case-insensitive,
73 but arguments to directives are often case sensitive. Lines
74 that begin with the hash character "#" are considered
75 comments, and are ignored. Comments may <strong>not</strong> be
76 included on a line after a configuration directive. Blank lines
77 and white space occurring before a directive are ignored, so
78 you may indent directives for clarity.</p>
80 <p>The values of variables defined with the <directive
81 module="core">Define</directive> of or shell environment variables can
82 be used in configuration file lines using the syntax <code>${VAR}</code>.
83 If "VAR" is the name of a valid variable, the value of that variable is
84 substituted into that spot in the configuration file line, and processing
85 continues as if that text were found directly in the configuration file.
86 Variables defined with <directive module="core">Define</directive> take
87 precedence over shell environment variables.
88 If the "VAR" variable is not found, the characters <code>${VAR}</code>
89 are left unchanged, and a warning is logged.
90 Variable names may not contain colon ":" characters, to avoid clashes with
91 <directive module="mod_rewrite">RewriteMap</directive>'s syntax.</p>
93 <p>Only shell environment variables defined before the server is started
94 can be used in expansions. Environment variables defined in the
95 configuration file itself, for example with <directive
96 module="mod_env">SetEnv</directive>, take effect too late to be used for
97 expansions in the configuration file.</p>
99 <p>The maximum length of a line in normal configuration files, after
100 variable substitution and joining any continued lines, is approximately
101 16 MiB. In <a href="configuring.xml#htaccess">.htaccess files</a>, the
102 maximum length is 8190 characters.</p>
104 <p>You can check your configuration files for syntax errors
105 without starting the server by using <code>apachectl
106 configtest</code> or the <code>-t</code> command line
109 <p>You can use <module>mod_info</module>'s <code>-DDUMP_CONFIG</code> to
110 dump the configuration with all included files and environment
111 variables resolved and all comments and non-matching
112 <directive module="core" type="section">IfDefine</directive> and
113 <directive module="core" type="section">IfModule</directive> sections
117 <section id="modules">
118 <title>Modules</title>
122 <module>mod_so</module>
125 <directive module="core" type="section">IfModule</directive>
126 <directive module="mod_so">LoadModule</directive>
130 <p>httpd is a modular server. This implies that only the most
131 basic functionality is included in the core server. Extended
132 features are available through <a
133 href="mod/">modules</a> which can be loaded
134 into httpd. By default, a <a
135 href="mod/module-dict.html#Status">base</a> set of modules is
136 included in the server at compile-time. If the server is
137 compiled to use <a href="dso.html">dynamically loaded</a>
138 modules, then modules can be compiled separately and added at
139 any time using the <directive module="mod_so">LoadModule</directive>
141 Otherwise, httpd must be recompiled to add or remove modules.
142 Configuration directives may be included conditional on a
143 presence of a particular module by enclosing them in an <directive
144 module="core" type="section">IfModule</directive> block. However,
145 <directive type="section">IfModule</directive> blocks are not
146 required, and in some cases may mask the fact that you're missing an
147 important module.</p>
149 <p>To see which modules are currently compiled into the server,
150 you can use the <code>-l</code> command line option. You can also
151 see what modules are loaded dynamically using the <code>-M</code>
152 command line option.</p>
156 <title>Scope of Directives</title>
160 <directive module="core" type="section">Directory</directive>
161 <directive module="core" type="section">DirectoryMatch</directive>
162 <directive module="core" type="section">Files</directive>
163 <directive module="core" type="section">FilesMatch</directive>
164 <directive module="core" type="section">Location</directive>
165 <directive module="core" type="section">LocationMatch</directive>
166 <directive module="core" type="section">VirtualHost</directive>
170 <p>Directives placed in the main configuration files apply to
171 the entire server. If you wish to change the configuration for
172 only a part of the server, you can scope your directives by
173 placing them in <directive module="core"
174 type="section">Directory</directive>, <directive module="core"
175 type="section">DirectoryMatch</directive>, <directive module="core"
176 type="section">Files</directive>, <directive module="core"
177 type="section">FilesMatch</directive>, <directive module="core"
178 type="section">Location</directive>, and <directive module="core"
179 type="section">LocationMatch</directive>
180 sections. These sections limit the application of the
181 directives which they enclose to particular filesystem
182 locations or URLs. They can also be nested, allowing for very
183 fine grained configuration.</p>
185 <p>httpd has the capability to serve many different websites
186 simultaneously. This is called <a href="vhosts/">Virtual
187 Hosting</a>. Directives can also be scoped by placing them
188 inside <directive module="core" type="section">VirtualHost</directive>
189 sections, so that they will only apply to requests for a
190 particular website.</p>
192 <p>Although most directives can be placed in any of these
193 sections, some directives do not make sense in some contexts.
194 For example, directives controlling process creation can only
195 be placed in the main server context. To find which directives
196 can be placed in which sections, check the <a
197 href="mod/directive-dict.html#Context">Context</a> of the
198 directive. For further information, we provide details on <a
199 href="sections.html">How Directory, Location and Files sections
203 <section id="htaccess">
204 <title>.htaccess Files</title>
208 <directive module="core">AccessFileName</directive>
209 <directive module="core">AllowOverride</directive>
213 <p>httpd allows for decentralized management of configuration
214 via special files placed inside the web tree. The special files
215 are usually called <code>.htaccess</code>, but any name can be
216 specified in the <directive module="core">AccessFileName</directive>
217 directive. Directives placed in <code>.htaccess</code> files
218 apply to the directory where you place the file, and all
219 sub-directories. The <code>.htaccess</code> files follow the
220 same syntax as the main configuration files. Since
221 <code>.htaccess</code> files are read on every request, changes
222 made in these files take immediate effect.</p>
224 <p>To find which directives can be placed in
225 <code>.htaccess</code> files, check the <a
226 href="mod/directive-dict.html#Context">Context</a> of the
227 directive. The server administrator further controls what
228 directives may be placed in <code>.htaccess</code> files by
229 configuring the <directive module="core">AllowOverride</directive>
230 directive in the main configuration files.</p>
232 <p>For more information on <code>.htaccess</code> files, see
233 the <a href="howto/htaccess.html">.htaccess tutorial</a>.</p>