Disable default option key binding

Question

In any text editor, when I type
⌥ p it inserts π at cursor
⌥ w it inserts ∑ at cursor
Thus every key when pressed with option ⌥ inserts some special character.

Question

How can I disable this ?

Why I want to disable this?

1. I hardly use these symbols
2. I am an hardcore emacs user, hence I always prefer shortcuts like
   • ^ A to move cursor to beginning, instead of Home
   • ^ n to next line, instead of ↓
   • ^ K to kill line
     Thus I always use Control + Key for every navigation in text.
     But since mac has some other functionaly for Option + Key I cannot use some thing like, ⌥ w to copy region

Note: - The reason I love Mac over Linux apart from Crispy UI, is its native support to emacs shortcuts. If shortcut with option modifier work well every text editor will be emacs for me.

Answer 1

Save the following to ~/Library/KeyBindings/DefaultKeyBinding.dict (create if necessary).

{ "~a" = (); "~b" = (); "~c" = (); "~d" = (); "~e" = (); "~f" = (); "~g" = (); "~h" = (); "~i" = (); "~j" = (); "~k" = (); "~l" = (); "~m" = (); "~n" = (); "~o" = (); "~p" = (); "~q" = (); "~r" = (); "~s" = (); "~t" = (); "~u" = (); "~v" = (); "~w" = (); "~x" = (); "~y" = (); "~z" = (); }

This disables all the ⌥<letter> combinations. Restart apps to take effect.

The DefaultKeyBinding.dict above is an old-style property list¹, defining key-value pairs using the syntax { key = value }. In this case, the keys are the key combinations to activate the method in the value.

Standard dictionary key symbols are used: ~ alt, ^ control, $ shift, @ command.
Therefore ~a means ⌥A (alt-A) and ^$1 would be ⌃⇧1 (control-shift-1).

The value for each of the keys is set to ()—empty parentheses without a method. As DefaultKeyBinding.dict overrides /S*/L*/Fr*/AppKit.*/R*/StandardKeyBinding.dict, the shortcut is defined to be without method and therefore does nothing. It's preferable to create your own key bindings file like this rather than editing the system one.

^{1 Feel free to use a new XML property list style if you prefer—it works the same.}

Answer 2

I found that using the Unicode hex input input source (System Preferences > Keyboard > Input Sources, then add source and select Other under languages) worked for me. Found this after trying to change input sources based on @exmaxx's suggestion. NOTE: Using ABC (my default) or US did not solve the problem for me.

Answer 3

For anyone finding this later and having problems with this.

I was unsuccessful doing this, and the other option with Ukelele has it's own problems (hard to remove default keyboard), so I ended up using BetterTouchTool to replace Option shortcuts with other actions.

Answer 4

The solution also might be to use different keyboard layout, e.g. U.S.:

• problems with "alt" keys: U.S. International, ABC
• solution: U.S.

Change it in System Preferences -> Keyboard -> Input Sources.

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I found the solution on Stack Overflow here so you might give the author a credit if it helped you also ;)