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Linux系统调用

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<TITLE>Syscall specifications of Linux - alarm</TITLE>
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<H2><A NAME="SEC85" HREF="syscalls_toc.html#SEC85" tppabs="http://personal.xfol.com/%7erezaie/syscall/syscalls_toc.html#SEC85">alarm</A></H2>
<P>
<H3>SYNOPSIS</H3>
<P>
<CODE>long alarm(long <VAR>seconds</VAR>);</CODE>
<P>
<H3>PARAMETERS</H3>
<P>
<VAR>seconds</VAR>: [in] the delay.
<P>
<H3>DESCRIPTION</H3>
<P>
If the call completes successfully, the taks will receive a
<CODE>SIGALARM</CODE> signal after a delay of <VAR>seconds</VAR> seconds. A delay
of zero seconds simply cancel the alarm. If an previous alarm was
activated when the call is made then the previous alarm is cancelled.
<P>
Internally, the call just sets an interruption timer.
<P>
<H3>RETURN VALUE</H3>
<P>
If a previous alarm was activated, the call returns the time delay
before the expiration of that previous alarm (now canceled). Otherwise,
it returns zero.
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