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<title>The configuration file</title>
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<h2 class="title">The configuration file</h2>
<p class="simpara">
The configuration file (<var class="filename">php.ini</var>)
is read when PHP starts up. For the server module versions of PHP,
this happens only once when the web server is started. For the
<acronym title="Common Gateway Interface">CGI</acronym> and <acronym title="Command Line Interpreter/Interface">CLI</acronym> versions, it happens on
every invocation.
</p>
<p class="para">
<var class="filename">php.ini</var> is searched for in these locations (in order):
<ul class="itemizedlist">
<li class="listitem">
<span class="simpara">
SAPI module specific location (<em>PHPIniDir</em> directive
in Apache 2, <em>-c</em> command line option in CGI and CLI,
<em>php_ini</em> parameter in NSAPI,
<em>PHP_INI_PATH</em> environment variable in THTTPD)
</span>
</li>
<li class="listitem">
<span class="simpara">
The <var class="varname"><var class="varname">PHPRC</var></var> environment variable. Before PHP 5.2.0,
this was checked after the registry key mentioned below.
</span>
</li>
<li class="listitem">
<span class="simpara">
As of PHP 5.2.0, the location of the <em>php.ini</em> file
can be set for different versions of PHP. The following registry keys
are examined in order:
<em>[HKEY_LOCAL_MACHINE\SOFTWARE\PHP\x.y.z]</em>,
<em>[HKEY_LOCAL_MACHINE\SOFTWARE\PHP\x.y]</em> and
<em>[HKEY_LOCAL_MACHINE\SOFTWARE\PHP\x]</em>, where
x, y and z mean the PHP major, minor and release versions. If there is a
value for <em>IniFilePath</em> in any of these keys, the first
one found will be used as the location of the <em>php.ini</em>
(Windows only).
</span>
</li>
<li class="listitem">
<span class="simpara">
<em>[HKEY_LOCAL_MACHINE\SOFTWARE\PHP]</em>, value of
<em>IniFilePath</em> (Windows only).
</span>
</li>
<li class="listitem">
<span class="simpara">
Current working directory (except CLI).
</span>
</li>
<li class="listitem">
<span class="simpara">
The web server's directory (for SAPI modules), or directory of PHP
(otherwise in Windows).
</span>
</li>
<li class="listitem">
<span class="simpara">
Windows directory (<var class="filename">C:\windows</var>
or <var class="filename">C:\winnt</var>) (for Windows), or
<em>--with-config-file-path</em> compile time option.
</span>
</li>
</ul>
</p>
<p class="para">
If <var class="filename">php-SAPI.ini</var> exists (where SAPI is the SAPI in use,
so, for example, <var class="filename">php-cli.ini</var> or
<var class="filename">php-apache.ini</var>), it is used instead of <var class="filename">php.ini</var>.
The SAPI name can be determined with <span class="function"><a href="function.php-sapi-name.html" class="function">php_sapi_name()</a></span>.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
The Apache web server changes the directory to root at startup, causing
PHP to attempt to read <var class="filename">php.ini</var> from the root filesystem if it exists.
</p>
</p></blockquote>
<p class="para">
Using environment variables can be used in <var class="filename">php.ini</var> as shown below.
</p>
<p class="para">
<div class="example" id="example-63">
<p><strong>Example #1 <var class="filename">php.ini</var> Environment Variables</strong></p>
<div class="example-contents">
<div class="inicode"><pre class="inicode">; PHP_MEMORY_LIMIT is taken from environment
memory_limit = ${PHP_MEMORY_LIMIT}</pre>
</div>
</div>
</div>
</p>
<p class="para">
The <var class="filename">php.ini</var> directives handled by extensions are documented
on the respective pages of the extensions themselves. A <a href="ini.html" class="link">list of
the core directives</a> is available in the appendix. Not all
PHP directives are necessarily documented in this manual: for a complete list
of directives available in your PHP version, please read your well commented
<var class="filename">php.ini</var> file. Alternatively, you may find
<a href="http://git.php.net/?p=php-src.git;a=blob;f=php.ini-production;hb=HEAD" class="link external">» the latest <var class="filename">php.ini</var></a> from Git
helpful too.
</p>
<p class="para">
<div class="example" id="example-64">
<p><strong>Example #2 <var class="filename">php.ini</var> example</strong></p>
<div class="example-contents">
<div class="inicode"><pre class="inicode">; any text on a line after an unquoted semicolon (;) is ignored
[php] ; section markers (text within square brackets) are also ignored
; Boolean values can be set to either:
; true, on, yes
; or false, off, no, none
register_globals = off
track_errors = yes
; you can enclose strings in double-quotes
include_path = ".:/usr/local/lib/php"
; backslashes are treated the same as any other character
include_path = ".;c:\php\lib"</pre>
</div>
</div>
</div>
</p>
<p class="para">
Since PHP 5.1.0, it is possible to refer to existing .ini variables from
within .ini files. Example: <em>open_basedir = ${open_basedir}
":/new/dir"</em>.
</p>
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