title: unix sed command matching a word
body: <p>I am trying to match a line and use sed command to substitute it. Some thing like</p>
  
  <pre><code>aaa = 10
   aaa =10
  aaa=10
  </code></pre>
  
  <p>My sed regular expression should match all those patterns and should replace with something like bbb=5. I tried with </p>
  
  <pre><code>     sed -i '/ *aaa *= */bbb=5' 
  </code></pre>
  
  <p>But this is not properly working for all the patterns. Any help will be really appreciable.</p>