This manpage is Copyright (C) 1992 Drew Eckhardt; and Copyright (C) 1993 Michael Haardt, Ian Jackson. %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under th...
NAMEalarm - set an alarm clock for delivery of a signal
#include <unistd.h> 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, any pending alarm is canceled.
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 previously scheduled alarm.
CONFORMING TOPOSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
NOTESalarm() and setitimer(2) share the same timer; calls to one will interfere with use of the other.
Alarms created by alarm() are preserved across execve(2) and are not inherited by children created via fork(2).
may be implemented using
mixing calls to
is a bad idea.
Scheduling delays can, as ever, cause the execution of the process to be delayed by an arbitrary amount of time.