#!/usr/bin/perl  

eval {
  local $SIG{ALRM} = sub { die('ALARM'); };
  alarm(5);

  #use forking open to start another processes
  unless ($pid = open REGEX, "-|")
  {
    print "starting long regex match...\n";
    
    #This string will take close to forever to match
    $_ = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+aaaa";
    print "matched\n" if
        /a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a*a
+*a*[b]/;

    exit;
  }
  
  while (<REGEX>) #read results from long running process
  {
    print "$_";
  }

  alarm(0);
};

if ($@ =~ /ALARM/)
{   
    print "got alarm\n";
    kill 9, $pid;
}
else
{
    print "no alarm\n"
}
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