what does screen command do in linux code example

Example: linux screen

Linux screen commands

# Starting Named Session
$ screen -S session_name

# Close screen (with id)
screen -X -S 12345 quit

#All screen list
$screen -ls

#Reattach to a Linux Screen
$ screen -r 12345 (screen id)

#Detach from Linux Screen Session
$ Ctrl+a d