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 argument.
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
232.
APPLICATION USAGE
sleep()
is thread-safe. It is not async-cancel-safe. A cancellation point
may occur when a thread is executing
sleep().
If a SIGALRM is generated for a multi-threaded
process, it may not be delivered to a thread currently
in
sleep().
See
sigwait(2)
man page for details.
In a multi-threaded process delivery of a SIGALRM to
a thread in
sleep()
simply causes
sleep()
to return without invoking the SIGALRM handler.
STANDARDS CONFORMANCE
sleep(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
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