(defparameter *shell* (uiop:launch-program "zsh" :input :stream :output :stream))
(defconst +buffer-size+ 1024)
(defvar *buff* (make-array +buffer-size+ :initial-element nil ))

(define-symbol-macro *output* (uiop:process-info-output *shell*))
(define-symbol-macro *input* (uiop:process-info-input *shell*))

(write-line "ps" (uiop:process-info-input *shell*))
(force-output (uiop:process-info-input *shell*))
(time 
(read-line *output*)

(read-sequence *buff* (uiop:process-info-output *shell*))


(defun read-output (&key (program *shell*) (to-string nil))
  (flet ((output ()
           (let ((stream (uiop:process-info-output program))
                 (first t))
             (loop while (or first (listen stream)) do
               (setf first nil)
               (princ (read-line stream))
               (fresh-line)))))
    (if to-string
        (read-output-string (output))
        (output))))

(defun exec (command &optional to-string)
  (write-line command (uiop:process-info-input *shell*))
  (force-output (process-info-input *shell*))
  (read-output :to-string to-string))