NAME

       alarm - set an alarm clock for delivery of a signal

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <unistd.h>

       unsigned int alarm(unsigned int seconds);

DESCRIPTION

       alarm()  arranges  for  a SIGALRM signal to be delivered to the calling process in seconds
       seconds.

       If seconds is zero, any pending alarm is canceled.

       In any event any previously set alarm() is canceled.

RETURN VALUE

       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.

STANDARDS

       POSIX.1-2008.

HISTORY

       POSIX.1-2001, SVr4, 4.3BSD.

NOTES

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

       Alarms created by alarm() are preserved across execve(2) and are not inherited by children
       created via fork(2).

       sleep(3)  may  be implemented using SIGALRM; mixing calls to 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.

SEE ALSO

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