Error Control Operators
Incrementing/Decrementing Operators
Operators
PHP Manual

## Execution Operators

PHP supports one execution operator: backticks (``). Note that these are not single-quotes! PHP will attempt to execute the contents of the backticks as a shell command; the output will be returned (i.e., it won't simply be dumped to output; it can be assigned to a variable). Use of the backtick operator is identical to shell_exec().

`<?php
$output = `ls -al`;
echo "<pre>$output</pre>";
?>`

> Note:

> The backtick operator is disabled when safe mode is enabled or shell_exec() is disabled.

> Note:

> Unlike some other languages, backticks cannot be used within double-quoted strings.

See also the manual section on Program Execution functions, popen() proc_open(), and Using PHP from the commandline.

Error Control Operators
Incrementing/Decrementing Operators
Operators
PHP Manual