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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.getenv" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<refnamediv>
<refname>getenv</refname>
<refpurpose>Gets the value of a single or all environment variables</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type class="union"><type>string</type><type>array</type><type>false</type></type><methodname>getenv</methodname>
<methodparam choice="opt"><type class="union"><type>string</type><type>null</type></type><parameter>name</parameter><initializer>&null;</initializer></methodparam>
<methodparam choice="opt"><type>bool</type><parameter>local_only</parameter><initializer>&false;</initializer></methodparam>
</methodsynopsis>
<para>
Gets the value of a single or all environment variables.
</para>
<para>
You can see a list of all the environmental variables by using
<function>phpinfo</function>. Many of these variables are listed within
<link xlink:href="&url.rfc;3875">RFC 3875</link>, specifically
section 4.1, "Request Meta-Variables".
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>name</parameter></term>
<listitem>
<para>
The variable name as a &string; or &null;.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>local_only</parameter></term>
<listitem>
<para>
When set to &true;, only local environment variables are returned, set by the operating system or putenv. It only has
an effect when <parameter>name</parameter> is a &string;.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
Returns the value of the environment variable
<parameter>name</parameter>, or &false; if the environment
variable <parameter>name</parameter> does not exist.
If <parameter>name</parameter> is &null;, all environment variables are
returned as an associative <type>array</type>.
</para>
</refsect1>
<refsect1 role="changelog">
&reftitle.changelog;
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
<row>
<entry>8.0.0</entry>
<entry>
The <parameter>name</parameter> is now nullable.
</entry>
</row>
<row>
<entry>7.1.0</entry>
<entry>
The <parameter>name</parameter> can now be omitted to retrieve an
associative <type>array</type> of all environment variables.
</entry>
</row>
<row>
<entry>7.0.9</entry>
<entry>
The <parameter>local_only</parameter> parameter has been added.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title><function>getenv</function> Example</title>
<programlisting role="php">
<![CDATA[
<?php
// Example use of getenv()
$ip = getenv('REMOTE_ADDR');
// Or simply use a Superglobal ($_SERVER or $_ENV)
$ip = $_SERVER['REMOTE_ADDR'];
// Safely get the value of an environment variable, ignoring whether
// or not it was set by a SAPI or has been changed with putenv
$ip = getenv('REMOTE_ADDR', true) ?: getenv('REMOTE_ADDR')
?>
]]>
</programlisting>
</example>
</para>
</refsect1>
<refsect1 role="notes">
&reftitle.notes;
<warning>
<para>
If PHP is running in a SAPI such as Fast CGI, this function will
always return the value of an environment variable set by the SAPI,
even if <function>putenv</function> has been used to set a local
environment variable of the same name. Use the <parameter>local_only</parameter>
parameter to return the value of locally-set environment variables.
</para>
</warning>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>putenv</function></member>
<member><function>apache_getenv</function></member>
<member><link linkend="language.variables.superglobals">Superglobals</link></member>
</simplelist>
</para>
</refsect1>
</refentry>
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