Execution OperatorsPHP ManualPrevChapter 10. OperatorsNextExecution 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). 1  2 $output = `ls -al`; 3 echo "<pre>$output</pre>"; 4  See also system(), passthru(), exec(), popen(), and escapeshellcmd(). PrevHomeNextError control OperatorsUpIncrementing/Decrementing Operators