| ALARM(3) | Library Functions Manual | ALARM(3) |
alarm — set signal
timer alarm
Standard C Library (libc, -lc)
#include
<unistd.h>
unsigned
alarm(unsigned
seconds);
The
alarm()
function sets a timer to deliver the signal SIGALRM
to the calling process after the specified number of
seconds. If an alarm has already been set with
alarm() but has not been delivered, another call to
alarm() will supersede the prior call. The request
alarm(0) voids the current
alarm and the signal SIGALRM will not be delivered.
Due to setitimer(2) restriction the maximum number of seconds allowed is 100000000.
The return value of alarm() is the amount
of time left on the timer from a previous call to
alarm(). If no alarm is currently set, the return
value is 0.
setitimer(2), sigaction(2), sigpause(2), sigvec(2), signal(3), sleep(3), ualarm(3), usleep(3)
An alarm() function appeared in
Version 7 AT&T UNIX.
| April 19, 1994 | macOS 15.0 |