ALARM(2)                   Linux Programmer's Manual                  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 previ-
       ously 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 inter-
       fere 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),  sig-
       nal(2), timer_create(2), timerfd_create(2), sleep(3), time(7)

COLOPHON
       This  page  is  part of release 4.16 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       https://www.kernel.org/doc/man-pages/.



Linux                             2017-05-03                          ALARM(2)