bind tmux prefix to OS X cmd key (or any other binding)

Question

I'm used to iTerm2 (or Terminal.app for this case) on OS X. But I want to move to use tmux (or screen, but the problem is similar to both apps).

So my idea is to have a single iTerm tab with a tmux session opened with multiple tabs. To do the transition I have a basic feature I need to configure on tmux: switch the the tab 'n' by using cmd + n (like Firefox, Chrome, iTerm2 itself, etc)

However I can't find a way of mapping the cmd key on the mac keyboard. I first tried to implement cmd as a prefix key, with no success. I've tried setting

set-option -g prefix M-a (hoping for Meta-a)

set-option -g prefix ^a (hoping for ^ to work)

but nothing works. Is this possible? I don't really need to bind the prefix to cmd, but I want to be able to change tmux tabs with cmd+n.

Thank you

Answer 1

You want to invoke a sequence of keystrokes (first Ctrl-b, then n ranging from 0 to 9).

Your best bet is to use a keyboard shortcut utility such as Butler or Keyboard Maestro to do this for you.

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Using Butler:

Select + » Smart Item » Keystrokes, configure the hotkey Cmd-1. Press Ctrl-B, then 1 for the Keystrokes. Configure it to be only valid in Terminal (or iTerm). It will warn you that other applications might not like it, but you know that already.

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Using Keyboard Maestro:

Create a new group on the left that is only available in Terminal (or iTerm).

Add a new item, triggered by Hot Key Trigger (Cmd-1) and add two Keystrokes to its actions: Ctrl-B and 1.

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You might also want to take a look at this topic -- doesn't use Command though, and didn't work for me using Terminal.

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From the tmux documentation:

Bind key key to command. Keys may be specified prefixed with ‘C-’ or ‘ˆ’ for ctrl keys, or ‘M-’ for alt (meta) keys. The −r flag indicates this key may repeat, see the repeat-time option.

They don't support a third modifier key.

Answer 2

In iTerm2, you can map shortcuts to hex codes that get sent into the terminal. Goto iTerm2 Preferences -> Keys. In Global Shortcut Keys, click the + and add type your desired shortcut like the cmd+1, which will be captured. Then select "Send Hex Code". In the box that appears, type the hex codes that you want sent to tmux separated by spaces. Ctrl-B is 0x02, so for "Ctrl-B 1", type "0x02 0x31". See here for more hex codes: http://www.nthelp.com/ascii.htm

I mapped Cmd with h,j,k,l for moving around between tmux panes, and Cmd with % and " for creating the splits. I'll probably do something similar to move between vim splits with one control key.

Answer 3

Special shortcuts can be made with Terminal.app. I just found out the other day, but this may have been possible prior to lion.

Go into Preferences > Settings and click on the "Keyboard" tab. Now you need to add a new keyboard shortcut by clicking on the plus icon below the box. Now you want to set a key combo that "Sends string to shell."

Example: Let's say I want to set M-LeftArrow to be mapped to prefix-p (previous window).

Key: Left Arrow 
Modifier: Option 
Action: send string to shell

Now just type in prefix-p into the input box where prefix is whatever you have set for tmux (I use cntrl-a so the box displays \001p). Note that if you make a mistake, delete characters will be inserted instead of actually deleting characters, so hit the "Delete one character" button to move backwards, in case you mess up.

Special characters I have set to make life easier:

M-Left  > Previous Window
M-Right > Next Window
M-Up    > Enter scrolling mode
M-Down  > Next Pane

You can also modify cntrl-anything and shift-anything, but do remember that these could interfere with your $EDITOR or other programs, so be careful about what special functions might be rendered useless.

Also, note that I could not figure out how to duplicate this functionality in iTerm2.

Answer 4

You may also want to consider the native (but very experimental) integration that iTerm2 offers with tmux: http://code.google.com/p/iterm2/wiki/TmuxIntegration

That way, when you press Cmd-D to split the screen iTerm2 will split the tab for you. This is great, because the split is native, so you can drag the edge in the middle to re-adjust widths, or you can select a pane by clicking. Ditto for new tabs/windows (but the shortcuts are slightly different -- otherwise you'd have no way to add non-tmux tabs).

And like tmux, if you detach and re-attach, everything will be saved for you.

There are two caveats though: * this is a very experimental feature and very flaky for me. * you will have to build tmux yourself (using the archive somewhere on the link above).

-Chris

Answer 5

You might also look at this blog post that has very detailed explanations about tmux/iterm integration: http://tangledhelix.com/blog/2012/04/28/iterm2-keymaps-for-tmux/