SLEEP
Section: C Library Functions (3)
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BSD mandoc
NAME
sleep
- suspend process execution for interval of seconds
SYNOPSIS
Fd #include <unistd.h>
Ft unsigned int
Fn sleep unsigned int seconds
DESCRIPTION
The
Fn sleep
function suspends execution of the calling process until either the
number of seconds specified by
Fa seconds
have elapsed or a signal is delivered to the calling process and its
action is to invoke a signal-catching function or to terminate the
process. The suspension time may be longer than requested due to the
scheduling of other activity by the system.
If a timer is already running on the process its state is saved.
If the value
Fa seconds
is more than or equal to the remaining clock time for the saved timer,
the sleep time is set to
the remaining clock time.
The state of the previous timer
is restored after
Fa seconds
has passed.
This function is implemented using
setitimer(2);
it requires eight system calls each time it is invoked.
A similar but less compatible function can be obtained with a single
select(2);
such a function would not restart after signals, but would not interfere
with other uses of
setitimer.
RETURN VALUE
If the
Fn sleep
function returns because the requested time has elapsed, the value
returned will be zero. If the
Fn sleep
function returns due to the delivery of a signal, the value returned
will be the unslept amount (the request time minus the time actually
slept) in seconds.
SEE ALSO
setitimer(2),
sigaction(2),
sigsuspend(2),
alarm(3),
pause(3),
usleep(3)
STANDARDS
The
Fn sleep
function conforms to
St -p1003.1-90 .
HISTORY
A
Fn sleep
function appeared in
AT&T System
v7 .
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- SEE ALSO
-
- STANDARDS
-
- HISTORY
-
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Time: 21:44:08 GMT, August 05, 2022