title: Change user id in linux
body: <p>Here is a short description of what I want to do:</p>
  
  <p>User tom has id 1000. I'm calling <code>usermod -u 2000 tom</code>.</p>
  
  <p>What happens exactly besides that the id of tom changes to 2000? Do files and folders which were owned by this user still remain by this user or do I have to explicitly set the owner again?</p>
  
  <p>Thanks for your help!</p>