title: how does a process in linux decides privileges it has
body: <p>I want to know how does a process in Linux decides what privileges it has?</p>
  
  <p>Suppose there is a binary program <code>Read_File</code> that reads from file <code>/home/myname/data.txt</code> and displays the contents of it to the STD output; now, how does <code>Read_File</code> decides whether or not it has permission to read <code>data.txt</code>, what type of ids it checks to decide the privileges? </p>