On Fri, 11 Dec 2020, Hauke Laging wrote:
Hello, I regularly experience that one of several screen windows freezes. This usually happens after some time of inactivity.
What are you doing in those windows that freeze up? What programs were runing? Just sitting at a shell prompt? An open editor session? Was that window local to your computer or had you ssh'd to a remote system?
^A q does not solve this problem. Are there any other features which can cause this effect? I don't know whether the cause of the problem was always the same. When it happened the last time I attached strace to the respective shell and learnt by this that the shell still gets input from screen and writes its regular output.
One possibility: ^S can 'freeze' a window/shell session. It's the 'XOFF' software flow-control character, a hold-over from back when terminals were connected via serial lines. ^Q is the 'XON' character that should resume output. Given that on US/QWERTY keyboards, the 'A' and 'S' keys are right next to each other, it is easy to accidentally hit ^S when reaching for ^A in screen. You might have to also try ^A^Q to get the session to resume. I have had individual windows freeze up in ways that I wasn't able to fix with combos of those key sequences and wind up having to :kill that window, but I've also had pretty good luck unfreezing with ^Q and/or ^S^Q, and sometimes ':flow off'. Check the man page FLOW-CONTROL section as well as about the '-f' screen flag, the 'defflow' and 'flow' .screenrc options about how to control and/or disable this feature inside of screen. -- Michael Parson Pflugerville, TX KF5LGQ
