A quick screen guide

Start a screen session

Detach from the screen session
Ctrl+a d
(Hit Ctrl+a quickly followed by hitting just d)

List current screen sessions
$ screen -ls
There is a screen on:
1119.pts-0.acer11 (Detached)
1 Socket in /run/screens/S-brm.
screen -list does the same thing

Attach to this screen session
$screen - r

Attach to an already attached screen
That is , if the session is already attached by someone else or somewhere else
$screen -x

Terminate the screen session
(Ctrl+a k)
(Hit Ctrl+a quickly followed by hitting k)

After terminating a screen session, you should see something like this, you are taken back to the prompt where you started or attached the session.
$ screen
[screen is terminating]

Now there are no screen session
$ screen -ls
No Sockets found in /run/screens/S-brm.

Alternate ways to terminate screen session is Ctrl+d or exit as you would on a shell session. But only Ctrl+a k asks for confirmation like this:
Really kill this window [y/n]

Attach to a session when there are multiple sessions
There are three sessions here:
$screen -ls
There are screens on:
1209.pts-0.acer11 (Detached)
1205.pts-0.acer11 (Detached)
1202.pts-0.acer11 (Detached)
3 Sockets in /run/screens/S-brm.

To attach to the middle one 1205.pts-0.acer11 (Detached):
$screen -r 1205.pts-0.acer11
or just
$screen -r 1205
If the session is already attached by someone else, somewhere
$screen -x 1205

To name a session while starting for easy reference
$screen -S SessionName

SessionName given will now appear in screen -ls output

To change the window title
$screen -t Newtitle

I find this useful to see where I am

How I can tell I am in a screen session and which session?
$ echo $STY
Compare the output from screen -ls. If you are not attached to any screen session, you get a blank output.

Want some more, Oliver?
man screen

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