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ALARM(2) System Calls Manual ALARM(2) NAME alarm, nap, pause - schedule timing delays SYNOPSIS unsigned alarm(seconds) unsigned seconds; void nap(ticks) void pause() DESCRIPTION Alarm causes signal SIGALRM, see signal(2), to be sent to the invoking process in the number of seconds given by the argument. Unless caught or ignored, the signal terminates the process. Alarm requests are not stacked; successive calls reset the alarm clock. If the argument is 0, any alarm request is canceled. Because the clock has a one second resolution, the signal may occur up to one second early; because of scheduling delays, resumption of execution of when the signal is caught may be delayed an arbitrary amount. The return value is the amount of time previously remaining in the alarm clock. Nap suspends execution of the current process for the specified number of clock ticks. If ticks is negative, it is taken to be zero; if it is greater than two seconds, it is taken to be two seconds. Pause only returns upon termination of a signal handler started during the pause. It is used to give up control while waiting for a signal, usually from kill (see signal(2)), alarm(2), or the terminal driver ttyld(4). SEE ALSO kill(1), signal(2), setjmp(3), sleep(3) BUGS If the argument to alarm is greater than 65535, it is treated as 65535. If the alarm clock expires during a call to alarm, the return value will be 0, and the signal will be delivered immediately after the sys- tem call returns. If the routine calling alarm saves the return value and later restores it, it will disable any alarm set by the signal han- dler. ALARM(2)