SLEEP(3) BSD Library Functions Manual SLEEP(3)NAMEsleep — suspend process execution for an interval measured in seconds
Standard C Library (libc, -lc)
sleep(unsigned int seconds);
The sleep() function suspends execution of the calling process until
either seconds seconds have elapsed or a signal is delivered to the
process and its action is to invoke a signal-catching function or to ter‐
minate the process. System activity may lengthen the sleep by an inde‐
This function is implemented using nanosleep(2) by pausing for seconds
seconds or until a signal occurs. Consequently, in this implementation,
sleeping has no effect on the state of process timers, and there is no
special handling for SIGALRM.
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 requested time minus the time actually slept) in seconds.
SEE ALSOnanosleep(2), usleep(3)STANDARDS
The sleep() function conforms to ISO/IEC 9945-1:1990 (“POSIX.1”).
A sleep() function appeared in Version 7 AT&T UNIX.
BSD February 13, 1998 BSD