Both my Mac and my Linux box seem to have survived the leap second, at least so far. Both systems just reported 23:59:59 taking two seconds. A friend with a MacOS 10.10 box says he saw 00:00:00 briefly. I saw that in 2012, and it’s a serious bug (the date flips too!) but didn’t today.
while :; do date; sleep 0.1; done