pause - stop until signal
pause() never returns normally. It is used to give up control while
waiting for a signal from kill(2V) or an interval timer, see
getitimer(2). Upon termination of a signal handler started during a
pause, pause() will return.
When it returns, pause() returns -1.
When it returns, pause() sets errno to:
EINTR A signal is caught by the calling process and control is
returned from the signal-catching function.
kill(2V), getitimer(2), select(2), sigpause(2V)
21 January 1990 PAUSE(3V)