title: sed - comment a matching line and x lines after it
body: <p>I need help with using sed to comment a matching lines and 4 lines which follows it.
  in a text file.</p>
  
  <p>my text file is like this:</p>
  
  <pre><code>[myprocess-a]
  property1=1
  property2=2
  property3=3
  property4=4
  
  [anotherprocess-b]
  property1=gffgg
  property3=gjdl
  property2=red
  property4=djfjf
  
  [myprocess-b]
  property1=1
  property4=4
  property2=2
  property3=3
  </code></pre>
  
  <p>I want to prefix # to all the lines having text '[myprocess' and 4 lines that follows it
  expected output:</p>
  
  <pre><code>#[myprocess-a]
  #property1=1
  #property2=2
  #property3=3
  #property4=4
  
  [anotherprocess-b]
  property1=gffgg
  property3=gjdl
  property2=red
  property4=djfjf
  
  #[myprocess-b]
  #property1=1
  #property4=4
  #property2=2
  #property3=3
  </code></pre>
  
  <p>Greatly appreciate your help on this.</p>