alarm(3) - NetBSD Manual Pages

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ALARM(3)                NetBSD 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 seconds after the call to alarm().  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.  The maximum
     number of seconds allowed is 2147483647.

     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.  If there is an error setting the timer, alarm() returns
     ((unsigned int) -1).


SEE ALSO

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


STANDARDS

     The alarm() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'').


HISTORY

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

NetBSD 10.1                     April 19, 1994                     NetBSD 10.1