Q: How to increase the size of the scrollback buffer in GNU screen How do I increase the number of lines that I can view in screen?
I want to view the lines from the point when I ran screen -S <screen_name> to the current operation. For example, how would I increase the buffer length to around 50000 lines?
I have already tried ^a :scrollback <number> but it does not increases the lines I can reach in my current terminal.

A: You cannot retroactively increase the scrollback buffer length in the current session in order to recover old lines that have already been discarded. However, if you change the current scrollback parameter setting (C-a :scrollback <number>), it will add more space for future terminal output. You can also set the defscrollback parameter to affect the initial scrollback setting for new windows.
If you want to set the default for all windows of all new screen sessions, make a ~/.screenrc file with
defscrollback 50000

or, if you only want a big scrollback sometimes, put it in a separate file, like ~/screenrc-50k-scrollback and invoke screen like this:
screen -S <screen_name> -c ~/screenrc-50k-scrollback

Check the current scrollback buffer capacity with C-a i (the info command).
(22,1)/(25,40)+50000 +flow G0[BBBB] 0(bash)
               ^^^^^

Reference: GNU Screen manual, Scrollback section

A: I don't know if I understood correctly what you asked, but if so I think you can just increase the value of Lines of scrollback property you can find on the Window menu item on the left of your Session configuration.
