tmux

Use for existing interactive tmux sessions. For one-shot commands, use normal shell. For new non-interactive background jobs, use background execution.

Target

Target the window where this session runs — not the session's active window.

A bare relative target like .1 is a trap. tmux fills the omitted window with the session's current (active) window — whatever window the attached client is showing — which is usually NOT the window Claude runs in. $TMUX_PANE only fixes the session, never the window. So .1 silently drifts to another window's pane 1 whenever the user is looking elsewhere.

Anchor to Claude's own pane instead. $TMUX_PANE is set in this session's env; resolve it to a session:window prefix and build an absolute target:

W=$(tmux display-message -p -t "$TMUX_PANE" '#{session_name}:#{window_index}')
# then target panes as "$W.1", "$W.2", ...

Each Bash call is a fresh shell, so set W in the same command block where you use it.

To reach a different window or session on purpose, use an explicit session:window.pane, e.g. shared:0.0.

List the panes in Claude's window:

W=$(tmux display-message -p -t "$TMUX_PANE" '#{session_name}:#{window_index}')
tmux list-panes -t "$W"

See

W=$(tmux display-message -p -t "$TMUX_PANE" '#{session_name}:#{window_index}')
tmux capture-pane -t "$W.1" -p          # current screen
tmux capture-pane -t "$W.1" -p -S -     # full scrollback
tmux capture-pane -t "$W.1" -p | tail -20

-p prints to stdout. -S - includes scrollback (bounded by history-limit). Full-screen apps (vim, less) show only the current screen, not past output.

Send

Send literal text and Enter separately, to avoid paste/newline surprises:

W=$(tmux display-message -p -t "$TMUX_PANE" '#{session_name}:#{window_index}')
tmux send-keys -t "$W.1" -l -- "Please continue"
tmux send-keys -t "$W.1" Enter

Special keys (set W first, as above):

tmux send-keys -t "$W.1" C-c
tmux send-keys -t "$W.1" C-d
tmux send-keys -t "$W.1" Escape

Use -l -- for arbitrary literal text. Approve or select a prompt only after reading it:

W=$(tmux display-message -p -t "$TMUX_PANE" '#{session_name}:#{window_index}')
tmux capture-pane -t "$W.1" -p | tail -20   # read first
tmux send-keys -t "$W.1" -l -- "y"
tmux send-keys -t "$W.1" Enter

Notes

• Target format is session:window.pane. A bare .pane resolves the omitted window to the session's active window, NOT to $TMUX_PANE's window — so it drifts. Always anchor with W=$(tmux display-message -p -t "$TMUX_PANE" '#{session_name}:#{window_index}') and target "$W.pane".
• capture-pane -p prints to stdout. -S - captures full scrollback.