(defun my-command-line ()
  (or   
   #+SBCL *posix-argv*  
   #+LISPWORKS system:*line-arguments-list*
   #+CMU extensions:*command-line-words*
   nil))

(defun my-getenv (name &optional default)
  #+CMU
  (let ((x (assoc name ext:*environment-list* 
		  :test #'string=))) 
    (if x (cdr x)  default)) 
  #-CMU 
  (or #+Allegro   (sys:getenv name)
      #+CLISP     (ext:getenv name) 
      #+ECL       (si:getenv name) 
      #+SBCL      (sb-unix::posix-getenv name) 
      #+LISPWORKS (lispworks:environment-variable name)
      default))

(defun sh (com &rest args) 
  (let ((path (which com)))
    (with-output-to-string (s)
      (with-open-stream 
          (files
           (sb-ext:process-output
            (sb-ext:run-program path args
                                :output s)))))))
 
(defun tmp-file () 
  (line1 (sh "mktemp")))

(defun tmp-dir () 
  (let* ((dir  (format nil "~a" (random 1000000000)))
        (path (make-pathname :directory
                          `(:absolute "tmp" ,dir))))
    (ensure-directories-exist path)
    (format nil "/tmp/~a" dir)))

(defun which (exe)
  (if (eql #\/ (char exe 0))
      exe
      (let* ((com   (format nil "which ~a" exe)))
        (line1  (sh "/bin/bash" "-c" com)))))