• Install a LISP compiler. We’ll use Steel Bank Common Lisp. Extract the downloaded archive and run install.sh. If the binary location is not /opt/sbcl/bin/sbcl note it.
• Install emacs sudo apt-get install emacs
• Set up the MELPA repository adding this to your ~/.emacs file

  (require 'package) ;; You might already have this line
  (add-to-list 'package-archives
             '("melpa" . "https://melpa.org/packages/"))
  (when (< emacs-major-version 24)
  ;; For important compatibility libraries like cl-lib
  (add-to-list 'package-archives '("gnu" . "http://elpa.gnu.org/packages/")))
  (package-initialize) ;; You might already have this line
  

• Install SLIME with M-x package-install RET slime RET
• Set up SLIME and the LISP compiler location in the ~/.emacs file

  ;; Set your lisp system and, optionally, some contribs
   (setq inferior-lisp-program "/opt/sbcl/bin/sbcl")
   (slime-setup '(slime-fancy))
  

  • Additionaly, this adds an hook that starts SLIME when you open a lisp file

    (add-hook 'slime-mode-hook
              (lambda ()
                (unless (slime-connected-p)
       
    (defun my-slime-setup ()
      (require 'slime)
      (slime-setup '(slime-fancy)))
    (defvar my--slime-setup-done nil)
    (defun my-slime-setup-once ()
      (unless my--slime-setup-done
        (my-slime-setup)
        (setq my--slime-setup-done t)))
    (defadvice lisp-mode (before my-slime-setup-once activate)
      (my-slime-setup-once))
        
    (my-slime-setup)
    

• Finally, run M-x slime. It will compile the backend and finally give you the prompt.