The following works pretty well.

(defvar packages '(pkg1 pkg2 magit))

(require 'package) (add-to-list 'package-archives '("melpa" . "http://melpa.milkbox.net/packages/") t)

(package-initialize) (package-refresh-contents)

(dolist (p packages) (when (not (package-installed-p p)) (package-install p)))