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OpenSolaris 2009.06 - man page for alarm (opensolaris section 2)

alarm(2)							   System Calls 							  alarm(2)

alarm - schedule an alarm signal
#include <unistd.h> unsigned int alarm(unsigned int seconds);
The alarm() function causes the system to generate a SIGALRM signal for the process after the number of real-time seconds specified by sec- onds have elapsed (see signal.h(3HEAD)). Processor scheduling delays may prevent the process from handling the signal as soon as it is generated. If seconds is 0, a pending alarm request, if any, is cancelled. If seconds is greater than LONG_MAX/hz, seconds is rounded down to LONG_MAX/hz. The value of hz is normally 100. Alarm requests are not stacked; only one SIGALRM generation can be scheduled in this manner; if the SIGALRM signal has not yet been gen- erated, 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(2) functions inherits the time left to an alarm signal in the old process's image.
If there is a previous alarm request with time remaining, alarm() returns a non-zero value that is the number of seconds until the previous request would have generated a SIGALRM signal. Otherwise, alarm() returns 0.
The alarm() function is always successful; no return value is reserved to indicate an error.
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+
exec(2), fork(2), signal.h(3HEAD), attributes(5), standards(5) SunOS 5.11 6 Jun 2007 alarm(2)