Library Functions Manual
NAME sleep — suspend process execution for interval of seconds
LIBRARY Standard C Library (libc, -lc)
SYNOPSIS #include <unistd.h>
sleep(unsigned int seconds);
DESCRIPTION The sleep() function suspends execution of the calling process until either the number of seconds specified by seconds have elapsed or a signal is delivered to the calling process and its action is to invoke a signal-catching function or to terminate the process. The suspension time may be longer than requested due to the scheduling of other activity by the system.
RETURN VALUES If the sleep() function returns because the requested time has elapsed, the value returned will be zero. If the sleep() function returns due to the delivery of a signal, the value returned will be the unslept amount (the request time minus the time actually slept) in seconds.
STANDARDS The sleep() function conforms to IEEE Std 1003.1-1990 (“POSIX.1”).
HISTORY A sleep() function appeared in Version 7 AT&T UNIX.