(PHP 5, PHP 7)
streamWrapper::unlink — Delete a file
$path
) : boolThis method is called in response to unlink().
Note:
In order for the appropriate error message to be returned this method should not be defined if the wrapper does not support removing files.
pathThe file URL which should be deleted.
成功时返回 TRUE， 或者在失败时返回 FALSE。
调用此方法失败将给出
E_WARNING（未实现）。
Note:
当合法的上下文传递给调用函数时，属性 streamWrapper::$context 会被改变。