回调函数执行exec

function exec_callback($command, $callback){
    $array = array();
    exec($command, $array, $ret);
    if(!empty($array)){
        foreach ($array as $line){
            call_user_func($callback, $line);
        }
    }
}

// example to use
function print_lines($line){
    echo "> $line\n";
}

exec_callback("ping -c 10 www.baidu.com 2>&1 &", 'print_lines');