screen

1. screen:
   
   screen -dmS <screen_name> <command>
exit
2. nohup:
   
   nohup <command> &
exit
3. at:
   
   echo "<command>" | at now
exit
4. disown:
   
   <command> &
disown -h
exit

1. Start screen using the command:
   $ screen -S <SessionName>

   The -S switch gives the session a name, which makes multiple screen sessions easier to manage.

2. Allow multiuser access in the screen session:
   CTRL-A
:multiuser on

3. Grant permission to the guest user to access the screen session:
   CTRL-A
:acladd <guest_user>

4. The guest user can now connect via:
   $ screen -x <host_user>/<SessionName>

# open screen session
screen 

# list screen sessions
screen -ls 

# reattach to screen session
screen -r <name of screen session> 

# attach to a not detached session
screen -x <name of screen session> 

# detach from unattached session
screen -d 

Note: ^A = Ctrl-a (Press the "a" key while holding down Control key)

detach from screen session attached to
^A d 

# open another session
^A c 

list the screen windows
^A w 

# print screen and save a hardcopy
^A h 

# go to next window
^A n 

# go to previous window
^A p

# lock screen
^A x