title: shell script - edit lines in shadow file (':' delimiter)
body: <p>In the following shadow-type file:</p>
  
  <pre><code>user1:*:11111:0:88888:7:::
  user2:*:11111:0:88888:7:::
  user3:!!:11111:0:88888:7:::
  user4:!!:11111:0:88888:7:::
  user5:!!:11111:0:88888:7:::
  user6:!!:11111:0:88888:7:::
  </code></pre>
  
  <p>I need find user 4, for example, and replace the '!!' with 'something_else'. Does anyone know how I could do this? </p>
  
  <p>EDIT: Sorry that I wasn't clear - the '!!' could be anything.</p>