Check out the "Program Execution functions" here :
 
    http://www.php.net/manual/en/ref.exec.php

As well as the `backtick` execution operator :

    http://www.php.net/manual/en/language.operators.execution.php

Consider exec() :

    exec — Execute an external program                :
    ---------------------------------------------------
    http://www.php.net/manual/en/function.exec.php