note 34190 deleted from ref.datetime by vincent

Note Submitter: bishop ---- Beware of your system clock; it's not guaranteed to be monotonic increasing. For example, say I'm your lazy system administrator, and I notice our system clock is slow by 1 minute. What do I do? Easy (wrong) answer: set the date ahead 1 minute Hard (right) answer: increase the rate at which seconds tick to "catch up" with the actual time. Anyway, if your script's doing something time sensitive (like profiling code), and I (lazy admin) set the clock ahead 1 minute, you'll find your run times are 1 minute longer than they'd otherwise be. As a corollary, the clock might be set back, and you find your script ran in less (or negative) time than it would've otherwise. So, beware when adding/subtracting the times given by gettimeofday() etc. There is no guarantee they represent wall clock time. If you're absolutely in need of authoritative timestamping, contact a stratum 1 or 2 time server (e.g., bonehed.lcs.mit.edu, ncnoc.ncren.net, etc)