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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)