Had the exact same experience interviewing for Amazon way back in 2005. I was still in college, and the answer he was looking for involved some obscure Linux/Unix command. I really felt defeated and thought “well I guess I’m just not enough of a hard core coder.” I still remember his smug attitude as well. Looking back it seems ridiculous, deciding a college student was not fit for a software engineer position because he didn’t know an obscure Linux command off-hand? Bizarre. But I guess back in 2005 there was much less demand for software engineers so they could afford to be absurdly selective.