alarm(3) [freebsd man page]

ALARM(3)						   BSD Library Functions Manual 						  ALARM(3)

NAME

     alarm -- set signal timer alarm

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <unistd.h>

     unsigned int
     alarm(unsigned int seconds);

DESCRIPTION

     This interface is made obsolete by setitimer(2).

     The alarm() function sets a timer to deliver the signal SIGALRM to the calling process after the specified number of seconds.  If an alarm
     has already been set with alarm() but has not been delivered, another call to alarm() will supersede the prior call.  The request alarm(0)
     voids the current alarm and the signal SIGALRM will not be delivered.

     Due to setitimer(2) restriction the maximum number of seconds allowed is 100000000.

RETURN VALUES

     The return value of alarm() is the amount of time left on the timer from a previous call to alarm().  If no alarm is currently set, the
     return value is 0.

SEE ALSO

     setitimer(2), sigaction(2), sigsuspend(2), signal(3), sleep(3), ualarm(3), usleep(3)

HISTORY

     An alarm() function appeared in Version 7 AT&T UNIX.

BSD
								  April 19, 1994							       BSD

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, no new alarm() is scheduled.

       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 pre-
       viously scheduled alarm.

CONFORMING TO

       SVr4, POSIX.1-2001, 4.3BSD.

NOTES

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

       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

       This page is part of release 3.44 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2008-06-12								  ALARM(2)