title: linux user login/logout log for computer restriction
body: <p>I would like to know how to log the login and logout of a user : it would be a mean to measure how much time someone has been connected in a month so far.</p>
  
  <p>I know it's possible to use the command "last". But this command is based on a file that has a r/w permission for the user, hence the possibility to change these data.
  I would like to log these data over two months.</p>
  
  <p>Why would I like to do that ? In fact, I would like to prevent a normal user to use a computer (in graphical mode mainly) more than an hour a day - except week-ends, and 10 hours in total a week.</p>
  
  <p>Cedric</p>
  
  <p>(System used : kubuntu,/ Programming language : bash script)</p>