Option key does not work as Meta in Tmux

Solution 1:

I would suggest using iTerm2 instead of the default Terminal.app, as it is better for many reasons.

Specifically, you would be interested in iTerm2's options to map left/right option as "+Esc", which works much better than trying to have it emulate Meta for every purpose I can think of or have tried.

This setting is located under:

• Preferences
  • Profiles
    • [select a profile]
      • Keys

Solution 2:

For other folks who find their way here via their favorite search engine, I was able to solve this problem by simply going to Preferences -> Profiles -> Keyboard and checking "Use Option as Meta key" for the terminal profile I'm using.

I'm running weechat under tmux, and default key bindings make heavy use of the meta key.

Solution 3:

I had the same problem and none of the answers provided here worked. That is, I too had the iTerm2 [Option] key remapped to [+Esc] (aka. "fallback"-[META]) in my "Preferences -> Profiles -> Keyboard", as described in the other answers, but still could not change my tmux pane layout with [CTRL]-[b], [+Esc/META]-[DIGIT].

Then I found that under "Preferences -> Keys", there is a "Navigation Shortcuts" where [Option] + (any) [DIGIT] is mapped to "switch split panes" (remember [Option] is remapped to [+Esc], so that's a clear collision). Therefore, after un-setting that (to an empty key value), I finally can again comfortably resize my tmux panes with [CTRL]-[b], [+Esc/META]-[DIGIT] (instead of having to use [CTRL]-[b], (the real) [Esc], and then the desired layout [DIGIT]).