alarm

alarm - set an alarm clock for delivery of a signal

#include <unistd.h>
 I unsigned int alarm(unsigned int  seconds );

R alarm () arranges for a SIGALRM signal to be delivered to the process in seconds seconds. If seconds is zero, no new R alarm () is scheduled. In any event any previously set R alarm () is canceled.

R alarm () returns the number of seconds remaining until any previously scheduled alarm was due to be delivered, or zero if there was no previously scheduled alarm.

SVr4, POSIX.1-2001, 4.3BSD

R alarm () and setitimer(2) share the same timer; calls to one will interfere with use of the other.

sleep(3) may be implemented using R SIGALRM ; mixing calls to R alarm () and sleep(3) is a bad idea. Scheduling delays can, as ever, cause the execution of the process to be delayed by an arbitrary amount of time.

gettimeofday(2), pause(2), select(2), setitimer(2), sigaction(2), signal(2), sleep(3), time(7)