title: PHP/Linux: Does 'kill -9' equate to SIGKILL?
body: <p>I'm looking at this PHP code for doing a signal trap:</p>
  
  <pre><code>&lt;?php
  /*
  SIGTERM for 'kill' default of -15
  SIGINT for control-c
  */
      declare(ticks = 1);
  
      pcntl_signal(SIGTERM, "signal_handler");
      pcntl_signal(SIGINT, "signal_handler");
  
      function signal_handler($signal) {
          switch($signal) {
              case SIGTERM:
                  print "Caught SIGTERM\n";
                  exit;
              case SIGKILL:
                  print "Caught SIGKILL\n";
                  exit;
              case SIGINT:
                  print "Caught SIGINT\n";
                  exit;
          }
      }
  
      while(1) {
          //
      }
  ?&gt;
  </code></pre>
  
  <p>Can SIGKILL be equated to a number option to the 'kill' command such as 'kill -9'? If not, what conditions would cause a SIGKILL signal? Thanks!</p>