The other forum was not precisely wrong, but double posting is against the rules. I'm not a moderator or anything, so don't pay any attention to me. Your question here is somewhat different than the first one anyway so maybe it's okay.

However, it's somewhat intriguing to think that there must be a better way, but the author of who.c choses not to use it. Could you elaborate on that train of thought, and maybe explain why you want to avoid using the tty access time?