sleep —
suspend process execution for interval measured in
seconds
#include
<unistd.h>
unsigned int
sleep(
unsigned
int seconds);
The
sleep() function suspends execution of
the calling process until either
seconds
seconds have elapsed or a signal is delivered to the 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.
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.
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
request time minus the time actually slept) in seconds.
sleep(1),
nanosleep(2)
The
sleep() function conforms to
IEEE Std 1003.1-1990
(“POSIX.1”).
A
sleep() system call first appeared in
Version 3 AT&T UNIX. In
Version 7 AT&T UNIX, it was removed and
replaced by a C library implementation based on
signal(3) and
alarm(3). For
OpenBSD 2.1, it was reimplemented as a wrapper around
the
nanosleep(2) system
call.
![[OpenBSD]](/openbsd.gif){kind=small}