We recommend not to turn off indentation.
Really, don’t do it.
If you want to see what it’d be, you will have to turn off a lot of “electric-foo” commands (such as automatic newlines and indentation after {, ;, etc.
Here’s how to turn it off after TAB. First, we define a function to turn it all off, then add this function to all the modes where you want it turned off.
(defun my-turn-indentation-off ()
(interactive)
(local-set-key (kbd "<tab>") 'tab-to-tab-stop))
(dolist (hook '(perl-mode-hook
cperl-mode-hook
c-mode-hook
c++-mode-hook
java-mode-hook))
(add-hook hook 'my-turn-indentation-off))
Now all you have to do is customize either one of these two variables: ‘tab-stop-list’ or ‘tab-width’.
If you just want to indent to the previous line, always, replace the definition of ‘my-turn-indentation-off’ with the following:
(defun my-turn-indentation-off () (interactive) (local-set-key (kbd "<tab>") 'indent-relative))
As said before, your time is better spent customizing the indentation engines.