<sleep $seconds [wake]>
sleep function pauses (sleeps) for
seconds (for each value of
sleep returns the number of seconds remaining to be slept (a
float), which is normally 0. However, if the "
sleep may wake up early and return a non-zero value,
if a signal was caught. (This can be used to wait for another process
to signal the script and wake it up, or to awaken ASAP/early on
sleep function was added Sep. 17 1996. The
flag was added Sep. 1 2000; previous versions behaved as if it were
Sleep durations with fractions of a second may be given, e.g. 1.5. However, the actual sleep duration may vary depending on the platform's clock resolution.