title: Using diff to compare a file with a variable
body: <p>In diff command am getting following error. Kindly assist how can I specify I want to see difference between a file and a variable:</p>
  
  <pre><code>$ current_unavail=ranjith
  $ cat /tmp/ran
  ranjith
  $ test=$(cat /tmp/ran)
  </code></pre>
  
  <p><strong>error which I am getting</strong></p>
  
  <pre><code>$ diff `$current_unavail` `$test`
  diff: missing operand after `diff'
  diff: Try `diff --help' for more information.
  </code></pre>