sleep - Suspend a program for a fixed period of time

Definition	#include <signal.h> int sleep(unsigned int sec); sleep suspends a program for sec seconds.
Return val.	Requested time minus actual time. If sleep was ended earlier than specified in sec, the time still remaining will be indicated (cf. note).
Note	sleep delays the program for sec seconds by internally calling the VPASS macro with a value of one second in a loop. Although the program is suspended for sec seconds when sleep is called, time continues to run for a previously set alarm clock (with alarm). The implications of this are detailed below: If the previously set alarm time is less than the sleep time, e.g. alarm(2); sleep(30); the alarm is triggered and the sleep call is ended after two "sleep" seconds have elapsed. If the previously set alarm time is greater than the sleep time, e.g. alarm(30); sleep(5); time continues to run on the alarm clock for 5 "sleeping" seconds. Following the sleep call, the alarm clock will be set at 25. The time for which the program is actually suspended may also deviate from sec for the following reasons: it may be up to one second shorter because "awakening" takes place at fixed 1-second intervals; it may be longer by any amount for priority reasons because the system has more important things to do.
See also	alarm, signal