I am a regular user of GNU screen. There must be some quirk of my setup that is causing a strange problem that I can't reproduce. Maybe you can help me isolate it.

My session has been going fine for a day or a week and then something happens, and suddenly the C-a stops being recognized by screen, but only when I am in an application. That application might be vim or python or R. When I'm in it, screen is unresponsive and I'm stuck in that application. I can regain control of screen by quitting the app and getting back to shell. Screen continues responding for new shells and for applications that were open in other windows before the problem began. When I start an application again I lose control again. If I open a totally new window and open a totally new application, I lose control. If I detach and reattach, the problem remains. Only by quitting and starting a new screen session do I get control back.

I don't know where to start diagnosing this problem. Any ideas?


  • I am a moderately experienced screen user.
  • I'm on OS X, in ITerm2, in zsh, but I think I've even had this problem in Terminal and bash.
  • I can share any .screenrc settings you'd like to see.
  • I lied above a little. I have C-a mapped to C-q. Maybe that matters.
  • 1
    Since control S/Q are normally used for xon/xoff flow control, that could be relevant... – Thomas Dickey Feb 22 '18 at 1:35
  • Bingo. Very good. It must take about a week for me to accidentally hit C-a f in vim while trying some other key combo. Solution is C-a :flow off and C-a :defflow off . Relevant docs here: gnu.org/software/screen/manual/html_node/… Thank you! – enfascination Feb 22 '18 at 2:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.