Schedules a SIGALRM signal.
Syntax
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#include <unistd.h>
unsigned int alarm (unsigned int seconds);
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Parameters
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- seconds
The number of real-time seconds to wait before generating a SIGALRM signal. A zero cancels any previously scheduled alarm request.
Return Values
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- 0
Success. There is no previously scheduled alarm.
- >0
Success. The number of seconds remaining on a previously scheduled alarm is returned.
Description
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The alarm() function causes the operating system to generate a SIGALRM signal for the calling process after the number of real-time seconds specified by the seconds parameter have elapsed. Operating system scheduling delays may prevent delivery of the signal until after the specified time.
Only one SIGALRM signal can be scheduled at a time. Any previously scheduled alarm is cancelled by the current alarm. A previously scheduled alarm is cancelled by passing zero in the seconds parameter.
Implementation Considerations
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Currently, alarm() does not cause a read timeout.
Errors
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None.
See Also
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fork(), pause(), sigaction(), <signal.h>, POSIX.1 (Section 3.4.1)
