title: UNIX sed command not removing spaces in cat output
body: <p>I have a file as below.</p>
  
  <pre><code>Hi this is first line
      this is second line
      this is third line
  </code></pre>
  
  <p>Expected is:</p>
  
  <pre><code>Hi this is first line
  this is second line
  this is third line
  </code></pre>
  
  <p>What i used is </p>
  
  <pre><code>cat file.txt | sed 's/ //g'
  </code></pre>
  
  <p>returns,</p>
  
  <pre><code>Hi this is first line
      this is second line
      this is third line
  </code></pre>