title: Waiting for network link to be up before continuing in bash
body: <p>Is there a way to check for successful network interface link for multiple interfaces in a bash script before continuing?</p>
  
  <p>Something like:</p>
  
  <pre><code>eth0 eth1 eth2 eth3 network interfaces are brought up
  Wait for link detection on all 4 interfaces
  Proceed
  </code></pre>