title: Null & empty string comparison in Bash
body: <p>I don't set any values for $pass_tc11; so it is returning null while echoing. How to compare it in <code>if</code> clause?</p>
  
  <p>Here is my code. <strong>I don't want "Hi" to be printed...</strong></p>
  
  <pre><code>-bash-3.00$ echo $pass_tc11
  
  -bash-3.00$ if [ "pass_tc11" != "" ]; then
  &gt; echo "hi"
  &gt; fi
  hi
  -bash-3.00$
  </code></pre>