Copy mode

alt y opens copy mode: a cursor over the pane’s history (1000 lines) that you can move, select from, and yank to your system clipboard — no mouse required. The [copy n] badge shows the scrollback offset; it becomes [copy n selecting] once you’ve marked a selection.

Keys	Action
↑ / k, ↓ / j	Move the cursor up/down a line, paging as needed
← / h, → / l	Move the cursor left/right a column
PgUp / PgDn	Page up / down
g / G	Jump to the oldest / newest line
v	Mark the selection anchor (press again to cancel)
y	Yank the selection (via OSC 52) and exit
q, Esc	Exit copy mode

Copying uses OSC 52, the same terminal-native clipboard escape tmux uses — it needs a terminal that supports it (ghostty, wezterm, kitty, alacritty, foot) but nothing else: no xclip/wl-copy, and it works the same over SSH.

Full-screen apps

Copy mode only reaches primary-screen history. Full-screen apps on the alternate screen (Claude Code, vim, less) keep no terminal scrollback and scroll their own viewport on the mouse wheel. For those, alt < / alt > scroll the focused pane by sending it wheel events — but only when the app has mouse tracking on, so a plain shell keeps copy mode.