Read GNU screen session without attaching to it

Question

I use GNU screen mostly to run commands that become non-interactive after some initial input.

I do not like navigating output in screen sessions, I feel it is a bit buggy.

Is there a way to access the history of a screen session without screen -r? (Not sure about the correct terminology here, I simply mean all the input and output that has occured in the screen session, not the history in the sense of the commands that were entered in the shell prompt).

Ideally, I'd like to do this with (1) bash/Linux builtins, (2) else with screen itself, (3) else with a Python package, (4) and only if none of these are possible with an external program.

(1: e.g. cat /run/screen/S-user/12345.pts-1.pc 2: e.g. screen --cat 12345 3: e.g. pip install screen; python -c 'import screen;print(screen.read_socket("12345"))' 4: e.g.sudo apt install screenreader; screenreader 12345)

Answer 1

expect can log a session transaction and can go unattended after some initial interaction input. This will allow you to run a command, interact with it, then type ~. to hand things over to expect until the program exits. Meanwhile, the out.1535209800 or whatever can be inspected.

#!/usr/bin/env expect
log_file out.[clock seconds]
spawn -noecho sh  ;# here be the command to run
interact {
  ~. { return }   ;# type this when done interacting
  ~~ { send "~" } ;# or this to get a literal ~ in the shell
}
if {[catch {
  expect {
    eof { exit }
    match_max { exp_continue }
    timeout { exp_continue }
  }
} oops ]} { puts stderr $oops; exit 1 }