alarm(2)

NAME

   alarm - set an alarm clock for delivery of a signal

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.

CONFORMING TO

   POSIX.1-2001, POSIX.1-2008, 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), sleep(3), time(7)

COLOPHON

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