NAME
sleep —
suspend thread execution for an
interval measured in seconds
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include
<unistd.h>
unsigned int
sleep(unsigned
int seconds);
DESCRIPTION
The
sleep()
function suspends execution of the calling thread until either
seconds seconds have elapsed or a signal is delivered
to the thread and its action is to invoke a signal-catching function or to
terminate the thread or process. System activity may lengthen the sleep by
an indeterminate amount.
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.
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 requested time
minus the time actually slept) in seconds.
SEE ALSO
STANDARDS
The sleep() function conforms to
IEEE Std 1003.1-1990 (“POSIX.1”).
HISTORY
A sleep() function appeared in
Version 7 AT&T UNIX.