extract archives from eshell

gistfile1.el

(defun if-string-match-then-result (to-match pairs)
  "Takes a string to match and a list of pairs, the first element
of the pairs is a regexp to test against the string, the second of
which is a return value if it matches."
  (catch 'break
    (dolist (val pairs)
      (if (string-match-p (car val) to-match)
	  (progn
	    (throw 'break (cadr val)))))
    (throw 'break nil)))

(defun eshell/extract (file)
  (eshell-command-result (concat (if-string-match-then-result
				  file
				  '((".*\.tar.bz2" "tar xjf")
				    (".*\.tar.gz" "tar xzf")
				    (".*\.bz2" "bunzip2")
				    (".*\.rar" "unrar x")
				    (".*\.gz" "gunzip")
				    (".*\.tar" "tar xf")
				    (".*\.tbz2" "tar xjf")
				    (".*\.tgz" "tar xzf")
				    (".*\.zip" "unzip")
				    (".*\.Z" "uncompress")
				    (".*" "echo 'Could not extract the requested file:'")))
		       " " file)))