sleep(3)
Name
sleep − suspend execution for interval
Syntax
unsigned
sleep(seconds)
unsigned seconds;
Description
The current process is suspended from execution for the number of seconds specified by the argument. The actual suspension time may be up to 1 second less than that requested, because scheduled wakeups occur at fixed 1-second intervals, and an arbitrary amount longer because of other activity in the system.
The routine is implemented by setting an interval timer and pausing until it occurs. The previous state of this timer is saved and restored. If the sleep time exceeds the time to the expiration of the previous timer, the process sleeps only until the signal would have occurred, and the signal is sent 1 second later.
Return Value
The value returned by sleep is the unslept amount(the requested time minus the time actually slept). This return value may be non-zero in cases where the caller had an alarm set to go off earlier than the end of the requested time, or where sleep was interrupted due to a caught signal(see ENVIRONMENT below).
Environment
POSIX
SYSTEM_FIVE
When your program is compiled in POSIX or System V mode, the sleep will be terminated by any caught signal. The sleep function will return following execution of the signal’s catching routine.