suspend execution for interval
cc . . . -lc
unsigned int sleep(unsigned int seconds);
The current process is suspended from execution for the number
of seconds specified by the argument.
The actual suspension time may be less than
that requested for two reasons: (1) Because scheduled wakeups
occur at fixed 1-second intervals, (on the
second, according to an internal clock) and (2) because any caught
signal terminates the sleep
following execution of that signal's catching routine.
Also, the suspension time may be longer than requested
by an arbitrary amount 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.
The routine is implemented by setting an alarm signal
and pausing until it (or some other signal) occurs.
The previous state of the alarm signal is saved and restored.
The calling program may have set up an alarm signal before calling
If the sleep time exceeds the time till such alarm signal,
the process sleeps only until the alarm signal would
The caller's alarm catch routine is executed just before the
sleep routine returns.
But if the sleep time is less than the time till such alarm,
the prior alarm time is reset to go off at the same time it
would have without the intervening sleep.
sleep is conformant with:
X/Open Portability Guide, Issue 3, 1989
IEEE POSIX Std 1003.1-1990 System Application Program Interface (API) [C Language] (ISO/IEC 9945-1)
NIST FIPS 151-1
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SCO OpenServer Release 5.0.7 -- 11 February 2003