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<title>Sets the value of an environment variable</title>
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<h1 class="refname">putenv</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">putenv</span> — <span class="dc-title">Sets the value of an environment variable</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.putenv-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>putenv</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$setting</code></span>
)</div>
<p class="para rdfs-comment">
Adds <em><code class="parameter">setting</code></em> to the server environment. The
environment variable will only exist for the duration of the current
request. At the end of the request the environment is restored to its
original state.
</p>
<p class="para">
Setting certain environment variables may be a potential security breach.
The <em>safe_mode_allowed_env_vars</em> directive contains a
comma-delimited list of prefixes. In Safe Mode, the user may only alter
environment variables whose names begin with the prefixes supplied by
this directive. By default, users will only be able to set environment
variables that begin with <em>PHP_</em> (e.g.
<em>PHP_FOO=BAR</em>). Note: if this directive is empty, PHP
will let the user modify ANY environment variable!
</p>
<p class="para">
The <em>safe_mode_protected_env_vars</em> directive contains a
comma-delimited list of environment variables, that the end user won't be
able to change using <span class="function"><strong>putenv()</strong></span>. These variables will
be protected even if <em>safe_mode_allowed_env_vars</em> is set
to allow to change them.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.putenv-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">setting</code></em></span>
<dd>
<p class="para">
The setting, like <em>"FOO=BAR"</em>
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.putenv-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> on success or <strong><code>FALSE</code></strong> on failure.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.putenv-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-517">
<p><strong>Example #1 Setting an environment variable</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />putenv</span><span style="color: #007700">(</span><span style="color: #DD0000">"UNIQID=</span><span style="color: #0000BB">$uniqid</span><span style="color: #DD0000">"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.putenv-notes">
<h3 class="title">Notes</h3>
<div class="warning"><strong class="warning">Warning</strong>
<p class="para">
The <em>safe_mode_allowed_env_vars</em> and
<em>safe_mode_protected_env_vars</em> directives only take
effect when <a href="features.safe-mode.html" class="link">safe_mode</a> is
enabled.
</p>
</div>
</div>
<div class="refsect1 seealso" id="refsect1-function.putenv-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.getenv.html" class="function" rel="rdfs-seeAlso">getenv()</a> - Gets the value of an environment variable</span></li>
</ul>
</p>
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