Cheatsheet: GNU Screen

Use screen -d -r <session_name> (or screen -dr) to force-detach the session from wherever it's currently attached and reattach it in your terminal. If the other end is unresponsive and won't detach cleanly, screen -D -r <session_name> forces a full detach (killing the other attachment) before reattaching.

Enter copy mode with Ctrl+a Esc (or Ctrl+a [), then use the arrow keys or Page Up/Page Down to scroll through the scrollback buffer. Press Esc or q to exit copy mode. The default scrollback buffer is small; increase it by adding defscrollback 10000 to ~/.screenrc.

Enter copy mode with Ctrl+a [, move the cursor to the start of the text and press Space (or Enter) to begin the selection, move to the end and press Space (or Enter) again to copy it into screen's paste buffer, then paste it anywhere with Ctrl+a ].

screen -r <name> reattaches a session for exclusive single-user access (it fails if the session is already attached elsewhere, unless you add -d to force-detach it first). screen -x <name> attaches to a session that stays attached elsewhere too, so multiple terminals can view/control the same session simultaneously — useful for pairing or monitoring.

From inside the session, type exit in every window (or run Ctrl+a then :quit) to terminate the whole session. From outside, screen -X -S <session_name> quit kills a named session without attaching to it first.