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This happens to me once every couple of hours. When I use the screen command and attempt to switch between windows by pressing ctrl+shift+a twice in succession, my session freezes.

This has happened to me when I've used putty to ssh to cloud servers and also to servers in my LAN at home.

Does anyone know any fixes to this?

  • Can you edit your question to include the contents of your ~/.screenrc? C-A C-A should have no effect, by default. Note, I'm following screen's convention of writing "ctrl+shift+a" as C-A – djeikyb Jan 5 '12 at 21:30
  • This happens to me a lot. I feel like it's not actually crashing but I am mis-pressing a key when doing Ctrl + A and this is locking it. – Mark Winterbottom Apr 1 '16 at 12:21
  • Yes it seems if I press Ctrl + A + S it will freeze the screen. The only way out is Ctrl + Q to quit and then come back into screen. – Mark Winterbottom Apr 1 '16 at 12:21
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I don't know about typing Ctrl-A twice, but Ctrl-a A should give a prompt to enter a new title for the current window. You might want to try Ctrl-q then Ctrl-d a couple of times until you see [Screen is terminating]. If you get that, then nothing has frozen, it was just waiting for input somewhere. What does your ~/.screenrc file look like, if you have one?

  • ctrl-q did the trick, thanks so much! Cute little twins! – user784637 Jan 7 '12 at 23:10
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By default C-A A does nothing. Do you have it bound to something in your .screenrc?

The only key combo I've had freeze my screen session is C-a s, which according to the screen manual does "xoff". I've never intentionally hit this combo. I used to blame it on screen freezing until I caught myself hitting C-a s instead of C-a a or C-a A.

Once you've hit that dastardly combo, the only graceful way out is to switch xoff to xon by using the key combo C-a q. Reading through the man page, it all has something to do with flow control. Near as I can tell it emulates Scroll Lock.

Read more about flow control in Gnu's Screen: manual

  • Will try this out the next time it happens and report back to you heh – user784637 Jan 4 '12 at 19:32
  • Same here; after a few freezes I realized it was C-a s, but didn't know about C-a q. – Chinasaur Sep 26 '14 at 7:40
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When using the screen command, C-a s will freeze your screen. You can unfreeze it with C-a q. To prevent C-a s from accidentally freezing your screen, put this line in your ~/.screenrc

bind s 
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I cannot find that key sequence in screen's manual page. Try ctrl+a twice instead, this is documented and you can be more lucky:

   C-a C-a     (other)       Toggle to the  window  displayed  previously.
                             Note  that  this binding defaults to the com-
                             mand character typed twice,  unless  overrid-
                             den.   For  instance,  if  you use the option
                             "-e]x", this command becomes "]]".

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