FreeBSD Manual Pages
alarm(2) System Calls alarm(2) NAME alarm - schedule an alarm signal SYNOPSIS #include <unistd.h> unsigned int alarm(unsigned int sec); DESCRIPTION The alarm() function causes the system to generate a SIGALRM signal for the process after the number of real-time seconds specified by seconds have elapsed (see signal.h(3HEAD)). Processor scheduling delays may prevent the process from handling the signal as soon as it is gener- ated. If seconds is 0, a pending alarm request, if any, is cancelled. Alarm requests are not stacked; only one SIGALRM generation can be scheduled in this manner; if the SIGALRM signal has not yet been gener- ated, the call will result in rescheduling the time at which the SIGALRM signal will be generated. The fork(2) function clears pending alarms in the child process. A new process image created by one of the exec functions inherits the time left to an alarm signal in the old process's image. RETURN VALUES If there is a previous alarm request with time remaining, alarm() re- turns a non-zero value that is the number of seconds until the previous request would have generated a SIGALRM signal. Otherwise, alarm() returns 0. ERRORS The alarm() function is always successful; no return value is reserved to indicate an error. ATTRIBUTES See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+ SEE ALSO exec(2), fork(2), signal.h(3HEAD), attributes(5), standards(5) SunOS 5.10 7 Jun 2001 alarm(2)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | ATTRIBUTES | SEE ALSO
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