sleep.3c (2010 09)

sleep(3C) sleep(3C)

NAME

sleep() - suspend execution for interval

SYNOPSIS

#include <unistd.h>

unsigned int sleep(unsigned int seconds);

DESCRIPTION

sleep() suspends the current process from execution for the number of seconds speciﬁed by the argu-

ment.

Actual suspension time can be less than that requested for two reasons:

• Scheduled wakeups occur at ﬁxed 1 second intervals (on the second, according to an internal clock),

and

• Any caught signal terminates the sleep following execution of that signal’s catching routine.

Suspension time can be an arbitrary amount longer than requested due to the scheduling of other activity

in the system. The value returned by

sleep()

is the "unslept" amount (the requested time minus the

time actually slept) in case the caller had an alarm set to go off earlier than the end of the requested

sleep() time, or premature arousal due to another caught signal.

seconds must be less than 2ˆ31.

APPLICATION USAGE

If a SIGALRM is generated for a multithreaded process, it may not be delivered to a thread currently in

sleep(). See the sigwait(2) manpage for details.