Fatal error: Can't use function return value in write context

Question

错误：

Fatal error: Can't use function return value in write context in /home/u566013465/public_html/2/inc/functions.php on line 2361 line 2361:

if( empty( shell_exec("which $command") ) ) {
    return false;
}

if( $config['debug'] ) {
    $start = microtime(true);
}

我有PHP 5.3

Answer 1

empty 函数只能用于变量，如果你传递任何其他东西，它会抛出一个解析错误：

$var  = shell_exec("which $command") ;
 if( empty( $var ) ) {
    return false;
}

if( $config['debug'] ) {
    $start = microtime(true);
}