title: How to signal an application without killing it in Linux?
body: <p>I have a watchdog application. It watches my main app which might crash for one reason or another (I know it is bad, but this is not the point).</p>
  
  <p>I programmed this watchdog to accept SIGUSR1 signals to stop monitoring my application presence. I signal it with </p>
  
  <pre><code>kill -SIGUSR1 `pidof myapp`
  </code></pre>
  
  <p>This works really well. My problem comes when I try to signal an older version of the watchdog which does not have this functionality built in. In this case, the kill signal kills the watchdog (terminates the process), which leads to further complications (rebooting of the device).</p>
  
  <p>Is there a way to signal my watchdog with SIGUSR1 so that it does not terminate if this particular signal is unhandled?</p>