title: how sort file with tab delimiter
body: <p>Now I generate one text file,band the values are stored as \t
  value1  value2  valu3.</p>
  
  <p>And I want to sort this text file as the value1</p>
  
  <pre><code>sort a.txt -o a.txt1
  </code></pre>
  
  <p>And found it happen wrong</p>
  
  <pre><code>google 1 1
  google 1 2
  google 1 3
  =google 1 4
  google 1 3
  </code></pre>
  
  <p>found =google was inserted between google.Why it happened,so stranged.</p>
  
  <p>And I tried <code>sort a.txt -t $'\t' -k 1 -o a.txt1</code> but it has the same issue.</p>