php-doc-en/reference/exec/functions/shell-exec.xml

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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<!-- splitted from ./en/functions/exec.xml, last change in rev 1.2 -->
<refentry xml:id="function.shell-exec" xmlns="http://docbook.org/ns/docbook">
<refnamediv>
<refname>shell_exec</refname>
<refpurpose>Execute command via shell and return the complete output as a string</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type class="union"><type>string</type><type>false</type><type>null</type></type><methodname>shell_exec</methodname>
<methodparam><type>string</type><parameter>command</parameter></methodparam>
</methodsynopsis>
<para>
This function is identical to the <link linkend="language.operators.execution">backtick operator</link>.
</para>
<note>
<para>
On Windows, the underlying pipe is opened in text mode which can cause the
function to fail for binary output. Consider to use <function>popen</function>
instead for such cases.
</para>
</note>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>command</parameter></term>
<listitem>
<para>
The command that will be executed.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
A &string; containing the output from the executed command, &false; if the pipe
cannot be established or &null; if an error occurs or the command produces no output.
</para>
<note>
<para>
This function can return &null; both when an error occurs or the program
produces no output. It is not possible to detect execution failures using
this function. <function>exec</function> should be used when access to the
program exit code is required.
</para>
</note>
</refsect1>
<refsect1 role="errors">
&reftitle.errors;
<para>
An <constant>E_WARNING</constant> level error is generated
when the pipe cannot be established.
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title>A <function>shell_exec</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
$output = shell_exec('ls -lart');
echo "<pre>$output</pre>";
?>
]]>
</programlisting>
</example>
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>exec</function></member>
<member><function>escapeshellcmd</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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