php获取机器运行的时间， 获取文本的内容

function get_dev_run_time() {    system("uptime > /var/uptime");    $file = fopen('/var/uptime', 'r');    if ($file) {        $buffer = fgets($file, 1024);        $str = explode(',', $buffer);        $str1 = strstr($str[0], "day", true);        if ($str1 != false) {            $str2 = strstr($str1, "up", false);            $days = substr($str2, 2);                        $str3 = strstr($str[1], "min", true);            if ($str3 != false) {                $hours = 0;                $mins = $str3;            } else {                $str4 = explode(':', $str[1]);                $hours = $str4[0];                $mins = $str4[1];            }        } else {            $days = 0;            $str2 = strstr($str[0], "min", true);            if ($str2 != false) {                $hours = 0;                $str3 = strstr($str2, "up", false);                $mins = substr($str3, 2);            } else {                $str3 = strstr($str[0], "up", false);                $time = substr($str3, 2);                $str4 = explode(':', $time);                $hours = $str4[0];                $mins = $str4[1];            }        }                fclose($file);    }        $format_time = $days."天".$hours."小时".$mins."分钟";        return $format_time;}