title: How to handle "-" in grep?
body: <p>Its been asked several times but its not clear to me yet.</p>
  
  <p>I have the following text in a file ( data.txt, tab delimeted ):</p>
  
  <pre><code>ABC    12
  ABC-AS    14
  DEF    18
  DEF-AS    9
  </code></pre>
  
  <p>Now I want to search for ABC and DEF, but not ABC-AS, DEF-AS as a result.</p>
  
  <pre><code>grep -w ABC data.txt
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>grep -w ABC data.txt
  ABC
  ABC-AS
  
  
  grep --no-group-separator -w "ABC" data.txt      
  ABC
  ABC-AS
  
  grep --group-separator="\t" -w "ABC" data.txt
  ABC
  ABC-AS
  </code></pre>