tmux/Q/How do I activate M-1 through M-7 to select a tmux pane layout?

• How do I activate to select a tmux/Pane layout?

  • My Answer

    • use Key/Meta 1 through Key/Meta 7

  • AI Answer

    • Short answer: M- means Key/Meta = Alt/Option (not Cmd). After pressing your prefix, press Option+1 through Option+7.

    • Why Cmd doesn't work

      • In tmux binding notation, M- is the Meta modifier, which maps to Alt (or Option on macOS) — not Command. Prefix Cmd+1 sends a key tmux does not recognize for these bindings.

    • Default layout bindings (-T prefix)

      • These are bound in the prefix key table, so the sequence is: press <prefix>, release, then press the key.

      • Key	Layout
        <prefix> Option+1	even-horizontal
        <prefix> Option+2	even-vertical
        <prefix> Option+3	main-horizontal
        <prefix> Option+4	main-vertical
        <prefix> Option+5	tiled
        <prefix> Option+6	main-horizontal-mirrored
        <prefix> Option+7	main-vertical-mirrored

    • macOS terminal requirement

      • The terminal emulator must forward Option as a Meta keypress. In iTerm2: Preferences → Profiles → Keys → set Left Option key to Esc+ (or Meta). In Terminal.app: Use Option as Meta key is not supported natively — consider switching to iTerm2.

    • Verify the binding is active

      • sh

        tmux list-keys -T prefix | grep "M-[1-7]"

      • If the output is empty, the bindings are not loaded. Source your config:
      • sh

        tmux source-file ~/.tmux.conf

    • Sources

      • tmux(1) man page — KEY BINDINGS
      • iTerm2 docs — Meta key