Obviously the person has to have a clue what they are doing. But I would never expect them to have the details memorized. "I'd look at the docs and stack overflow" is a valid answer. As long as they had the thought process established of what was being accomplished. They knew where they were going, they worked out a reasonable solution but maybe didn't remember some command flag. Memorization is useless. How does the person aproach and solve the problem is far more important.