Overtype mode in Terminal.app As a Linux/Windows user, I am used to switching temporarily to Overtype Mode when using the command prompt.

As a new user to the Mac world, I do not know how to change text input mode from normal (i.e. Insert Mode) to Overtype Mode.
This is of particular use to me at the command prompt, but also in text editors (eg TextWrangler or Sublime).

Anyone know of ways (using the keyboard only) to toggle between the two modes? (Solutions involving a mouse are not solutions, because I could simply select the text using the keyboard and re-type...but this is not what I am asking).

Any help appreciated.
I don't have access to my Mac right now, but on my Linux machine I'm set up to use zsh as my default shell.  It looks like you can do this on Mac too.  Once you're in zsh, you can easily use Vim keybindings  (I guess it may also work in Bash?) by running set -o vi.
With Vim bindings active, you can press ESC to go to Command Mode, then use any normal Vim keys including R to switch to Overtype mode.
PS: To go back to Emacs bindings use set -o emacs.