title: How does "Logout Everywhere" work in PHP?
body: <p>I just found out that stackoverflow has a link to logout every logged computers.</p>
  
  <p>So..I thought about how to implement same functionality in PHP. I came up with using session_set_save_haldner to control write() method. In write() method, I can make a session file start with user's username. For example, a user john might have session files john_kdkajdkak, and john_29039dla. When John clicks "Logout Everywhere", I can write a code that finds filenames start with "john" then remove them to clear sessions.</p>
  
  <p>are there any other better solutions? How did you implement it if you already made it work?</p>