arcsin(x)

turn off color

Do not use colors even if the terminal is capable (still allows the buffer mode to do syntax highlighting with bold text, etc): 
emacs --color=no
Disable (all) major-mode syntax highlighting: 
(global-font-lock-mode -1)
People suggest using the following in a loop over all font faces: 
(set-face-attribute face nil :foreground nil :background nil)
M-x customize-face can be used over a particular keyword in a buffer to change syntax highlighting properties

M-x customize-themes to choose a color theme (includes dark themes). Consider fxn/monochrome-theme.el

installing packages

Install a package from MELPA/ELPA (useful for installing language modes) 
M-x package-install package-name

eval a lisp expression in the current buffer and print the value in the minibuffer

M-:
for example 
M-: major-mode
to show the current major mode

force a mode on a file, put at end of text

  // Local Variables:
  // mode: c++
  // End:

goto an offset in the file

  M-x goto-char
Short cut: 
  M-g c

register commands

point-to-register: C-x r SPC
register-to-point: C-x j <register id>
copy-to-register:  C-x r x
insert-register:   C-x r g
view-register: -

highlight or remove useless whitespace

To show trailing whitespace 
(setq-default trailing-whitespace t)
in .emacs file. To remove tailing whitespace in a buffer, type 
M-x delete-trailing-whitespace

code folding

  use hide/show minor mode (hs-minor-mode)
  M-x hs-minor-mode

  add the minor mode to all programming modes
  (add-hook 'prog-mode-hook #'hs-minor-mode)
  

  C-c @ C-M-h    hide all (hs-hide-all)
  C-c @ C-h      hide block (hs-hide-block)
  C-c @ C-s      show block (hs-show-block)

  C-c @ C-e      toggle block (some particular about the pos to work)
  C-c @ C-a      show all
  C-c @ C-l      hide all (when pos outside of all blocks in the file)

.emacs file

; this is for shells that set either delete or backspace
; as ctrl h use M-x help to get to help instead
(global-set-key "\C-h" 'backward-delete-char)
; set the tab width slightly smaller
(setq default-tab-width 4)
;; do not display a splash screen on startup for emacs 22
(setq inhibit-splash-screen t)

;; turn off menu bar in terminal
(if (not window-system)
(menu-bar-mode -1))

;; don't use tabs to indent, may or may not want this
;; to insert a tab C-q 
(setq-default indent-tabs-mode nil)

(add-hook 'prog-mode-hook #'hs-minor-mode)

;; show trailing whitespace
(setq-default show-trailing-whitespace t)
- to make the elisp debugger window go away hit 'q' in the buffer

tramp: allows you to edit files remotely through ssh as well as other methods. you can just open a file using the normal scp path syntax.

emacs keybindings

under gnome 3

gsettings set org.gnome.desktop.interface gtk-key-theme "Emacs"

fill-paragraph

M-q is 'fill-paragraph' reflows text to justify it

Desktop Keybindings

under xfce

xfconf-query -c xsettings -p /Gtk/KeyThemeName -s Emacs

may need to add --create --type string to above