Setting SLIME in emacs

Top answer is a little bit old.

Nowadays emacs has an official package manager. You can install slime via MELPA repository. First setup MELPA, then M-x package-install RET slime RET.

After that you can set your inferior-lisp-program like the top answer explained.

Some Linuxes come with CMUCL preinstalled, but since you seem to want to use SBCL, you would need to install it.

In terminal, or in Emacs M-xshell. If you are using Debian-like distro, you can use apt-get or aptitude with the following:

$ sudo apt-get install sbcl

or

$ sudo aptitude install sbcl

on RHEL-like distro:

$ sudo yum install sbcl

After SBCL is installed, you can set inferior-lisp-program to "sbcl".

Also, I'd advise to install SLIME through quicklisp-slime-helper

You would need to install some Lisp you like (let it be SBCL for this purpose, as described above), then, in the same shell do this:

(Suppose you are on a Debian-like Linux)

$ sudo apt-get install wget
$ cd ~/Downloads
$ wget http://beta.quicklisp.org/quicklisp.lisp
$ sbcl --load ./quicklisp.lisp

wait until you see Lisp shell prompt,

* (quicklisp-quickstart:install)
* (ql:add-to-init-file)
* (ql:quickload "quicklisp-slime-helper")
* (quit)

now you are back in the regular shell. Launch Emacs, if not open yet. C-f x~/.emacs. Add the lines below to it (instead of what you posted above):

(load (expand-file-name "~/quicklisp/slime-helper.el"))
(setq inferior-lisp-program "sbcl")

Or replace "sbcl" with the Lisp implementation you installed.

Look into Quicklisp documentation for more information. You will find that you will be using Quicklisp later anyway, so it's useful you get it all in one place from the start.