Setting caps lock key to CTRL but still function as caps lock if I press for long enough I just started out using tmux, so I figured I would set my Caps lock key equal to the Ctrl key.

Though sometimes I do need the Caps lock key. I don't care if it requires playing with the Terminal or system files, I'm not afraid of that. However it would be nice if I could just run Terminal commands so that I can put it in a script. Also, if possible, it would be nice if it doesn't require extra software, although if it's necessary then there's no problem.

How can I make it so that it's normally a Ctrl key, but if I press it for say 5 seconds it triggers a normal Caps lock. I was wondering, how can I do this?
Using KeyRemap4MacBook, you could add this to private.xml:

&lt;autogen&gt;--HoldingKeyToKey-- KeyCode::CONTROL_L, KeyCode::CONTROL_L, KeyCode::VK_NONE, KeyCode::CAPSLOCK, Option::NOREPEAT&lt;/autogen&gt;

The threshold for holding a key is 0.2 s by default, but it can be changed in the second tab.

This would change fn+caps lock (control) to caps lock:

&lt;autogen&gt;--KeyToKey-- KeyCode::CONTROL_L, ModifierFlag::FN, KeyCode::CAPSLOCK&lt;/autogen&gt;