How to disable auto indent in Emacs globally or only for some modes?
I have a number of packages installed for RubyOnRails (ruby, html, js, css).
Let's say I want to disable autoindent for css-mode.
You may want to look for variable names containing the word electric. (This is the common Emacs parlance for actions which occur automatically when particular visible characters are typed.)
In this instance, M-x apropos-variable RET electric RET shows me that there is a css-electric-keys variable containing a list of "Self inserting keys which should trigger re-indentation."
You could use M-x customize-variable RET css-electric-keys RET to set this list to nil, or add (setq css-electric-keys nil) to your init file.
Sometimes a minor mode is used to implement electric behaviours, so that you can switch them on and off more easily. Those would likely be found via M-x apropos-command RET electric RET, and you would probably use a major mode hook to ensure that the electric minor mode was disabled, in a similar fashion to this:
(add-hook 'MAJORMODE-mode-hook 'my-MAJORMODE-mode-hook)
(defun my-MAJORMODE-mode-hook ()
(ELECTRICMODE-mode 0))