ALARM(2) Linux Programmer's Manual ALARM(2)NAMEalarm - set an alarm clock for delivery of a signal
unsigned int alarm(unsigned int seconds);
DESCRIPTIONalarm() 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 VALUEalarm() 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.
SVr4, POSIX.1-2001, 4.3BSD.
NOTESalarm() and setitimer(2) share the same timer; calls to one will inter‐
fere 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 ALSOgettimeofday(2), pause(2), select(2), setitimer(2), sigaction(2), sig‐
nal(2), sleep(3), time(7)COLOPHON
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Linux 2008-06-12 ALARM(2)