Handle a signal: Difference between revisions
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(Add SIGQUIT since per the task description SIGQUIT is more appropriate that SIGINT (see perl example) see discussion.) |
(demonstrate the power or signal handling) |
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=={{header|Perl}}== |
=={{header|Perl}}== |
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Before version 5.8 <tt>sleep</tt> requires an integer argument, so we'll spin (There exist more obtuse methods) |
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Perl's (in fact Unix's) <tt>sleep</tt> doesn't handle non-integral arguments correctly on some platforms, so this program uses the select syscall for timeout. |
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<lang perl> |
<lang perl> |
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my $start = time; # seconds since epohc |
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my $arlm=5; # every 5 seconds show how we're doing |
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my $i; |
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$SIG{QUIT} = sub |
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{print " Ran for ", time - $start, " seconds.\n"; die; }; |
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$SIG{INT} = sub |
$SIG{INT} = sub |
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{print |
{print " Running for ", time - $start, " seconds.\n"; }; |
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$SIG{ALRM} = sub |
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exit;}; |
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{print " After $arlm seconds i= $i. Executing for ", time - $start, " seconds.\n"; alarm $arlm }; |
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alarm $arlm; # trigger ALaRM after we've run for a while |
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print " ^C to inerrupt, ^\\ to quit, takes a break at $arlm seconds \n"; |
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while ( 1 ) { |
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for ( $w=11935000; $w--; $w>0 ){}; # spinning is bad, but hey it's only a demo |
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} |
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^C to inerrupt, ^\ to quit, takes a break at 5 seconds |
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1 |
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2 |
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^C Running for 1 seconds. |
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3 |
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4 |
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^C Running for 2 seconds. |
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5 |
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6 |
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^C Running for 3 seconds. |
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8 |
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10 |
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After 5 seconds i= 10. Executing for 5 seconds. |
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After 5 seconds i= 20. Executing for 10 seconds. |
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^\ Ran for 11 seconds. |
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Died at 0.pl line 6.. |
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for (my $n = 0 ;; select(undef, undef, undef, .5)) |
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This example does the required task: |
This example does the required task: |
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