| ALARM(3) | Library Functions Manual | ALARM(3) | 
alarm —
#include <unistd.h>
unsigned int
  
  alarm(unsigned
    int seconds);
The alarm() function sets a timer to
    deliver the signal SIGALRM to the calling process
    seconds after the call to
    alarm(). 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. The maximum number of
    seconds allowed is 2147483647.
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. If there is an error setting the timer,
    alarm() returns ((unsigned int) -1).
alarm() function conforms to IEEE
  Std 1003.1-1990 (“POSIX.1”).
alarm() function appeared in
  Version 7 AT&T UNIX.
| April 19, 1994 | NetBSD 10.0 |