<?xml version="1.0" encoding="utf-8"?>
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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.popen">
 <refnamediv>
  <refname>popen</refname>
  <refpurpose>Opens process file pointer</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>resource</type><methodname>popen</methodname>
   <methodparam><type>string</type><parameter>command</parameter></methodparam>
   <methodparam><type>string</type><parameter>mode</parameter></methodparam>
  </methodsynopsis>
  <para>
   Opens a pipe to a process executed by forking the command given
   by command.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>command</parameter></term>
     <listitem>
      <para>
       The command
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>mode</parameter></term>
     <listitem>
      <para>
       The mode
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns a file pointer identical to that returned by
   <function>fopen</function>, except that it is unidirectional (may
   only be used for reading or writing) and must be closed with
   <function>pclose</function>. This pointer may be used with
   <function>fgets</function>, <function>fgetss</function>, and
   <function>fwrite</function>.
  </para>
  <para>
   If an error occurs, returns &false;.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>popen</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$handle = popen("/bin/ls", "r");
?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   If the command to be executed could not be found, a valid
   resource is returned. This may seem odd, but makes sense; it
   allows you to access any error message returned by the shell:
   <example>
    <title><function>popen</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
error_reporting(E_ALL);

/* Add redirection so we can get stderr. */
$handle = popen('/path/to/executable 2>&1', 'r');
echo "'$handle'; " . gettype($handle) . "\n";
$read = fread($handle, 2096);
echo $read;
pclose($handle);
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 
 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    If you're looking for bi-directional support (two-way), use
    <function>proc_open</function>.
   </para>
  </note>
  &note.exec-path;
  &warn.sm.exec;
 </refsect1>
 
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>pclose</function></member>
    <member><function>fopen</function></member>
    <member><function>proc_open</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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