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Accepted
wlk
Asked: 2011-04-11 08:30:13 +0800 CST

How to check if I'm in screen session?

  • 772

I need it to determine if hitting ctrl+d would disconnect me from server or just close current screen.

Is it somehow possible to check if I'm right now in screen session?

gnu-screen console

9 Answers

  1. Best Answer

    You can look at the $STY variable (a variable set by the screen command). If it is not "" then you are in a screen session.

    I am in screen

    $ echo $STY 
29624.pts-1.iain-10-04
$

    I am not in screen

    $ echo $STY

$
    • 141

  2. You can look at the $TERM variable.

    echo $TERM

    If it's a screen session, the term variable should return "screen".

    root@deore:/volumes# echo $TERM
screen

    Ctrl-a -d (to exit screen)

    root@deore:/volumes# echo $TERM
xterm

    Also check: https://stackoverflow.com/questions/3472287/how-do-you-tell-if-the-current-terminal-session-is-in-gnu-screen

    • 51

  3. Unless you have changed the default key bindings, you can do Ctrl+a -> Ctrl+t, which will show the time, if you are in screen. This will work even if you have ssh:d away somewhere else, unlike the other suggestions.

    • 34

  4. The caption command in the ~/.screenrc is a nice way to differentiate a screen session.

    I'm personally using this:

    $ cat ~/.screenrc
caption always "%{= kc}Screen session on %H (system load: %l)%-28=%{= .m}%D %d.%m.%Y %0c"

    It adds a line like this one at the bottom of the screen:

    Screen session on gbook (system load: 1,75 1,74 1,68)                   Lun 05.01.2015 13:01

    With the first part (system name + load) in green and the date in pink. Useful and hard to miss!

    • 22

  5. I have found another solution:
    Modify your .screenrc, so my screen session looks completely different from normal terminal.

    • 7

  6. Better answer (in my opinion), inspired by this, just type the following:

    pstree -s $$

    If you get something like this:

    systemd───sshd───sshd───bash───screen───screen───bash───pstree

    … then you are in screen.

    This is true not only for screen, but also for any kind of process (like script, nested bash or other shells) opening a nested shell, and this can even also show nested screen calls (if several not consecutive occurrences exists).

    • 4

  7. If you are looking at a command line prompt, you can just type something, anything, and hit Ctrl+A. If your cursor jumps to the beginning of the prompt, you're not inside a screen. If you additionally have to hit A, then you are.

    • 0

  8. Do a screen -ls. It's going to explicitly indicate Attached versus Detached status.

    Example attached:

    $ screen -ls | grep tached
3132.pts-0.esavo00      (Attached)

    Example detached:

    $ screen -ls |grep tached
3132.pts-0.esavo00  (Detached)
    • -1 
  9. screen -ls

    to view your sessions and

    screen -r sessioninfo

    to reconnect to a disconnected one, if detached.

    screen -D -r sessioninfo

    to reconnect to a disconnected one.

    • -1