title: How to add a user without using the 'useradd' or 'adduser' commands in RHEL6.3?
body: <p>I want to add a user in a RHEL6.3 OS without using <code>useradd</code> or <code>adduser</code> command. 
  I know that I have to edit in 4 files i.e passwd, group, shadow and gshadow. </p>
  
  <p>But please tell me what exactly I have to edit? </p>