2016-10-11 *epfl_roaming +/var/run/epfl_roaming + --list_users

• SEMAPHORE_LOCK_FILE : /tmp/epfl_roaming_global_lock -> /var/run/epfl_roaming/global_lock
• SESSIONS_COUNT_FILE : /tmp/epfl_count_username -> /var/run/epfl_roaming/sessions_count

+ epfl_roaming.py --list_users : List users currently logged in and how many sessions they have
+ if users has no session anymore -> remove him from SESSIONS_COUNT_FILE
FIX epfl_roaming.py --on_halt set count to 0 (not -=1)
+ on_halt manages also guests