Emacs call-process as sudo

Question

UPDATE

I have accepted @Sean answer, with some small modifications.

(defun sudo-shell-command (buffer password command)
  (let ((proc (start-process-shell-command
           "*sudo*"
           buffer
           (concat "sudo bash -c "
                   (shell-quote-argument command)))))
    ;;; Added to @Sean answer to display the passed buffer
    (display-buffer buffer '((display-buffer . nil)) nil)
    (process-send-string proc password)
    (process-send-string proc "\r")
    (process-send-eof proc)))

(defun sudo-bundle-install (password)
  (interactive (list (read-passwd "Sudo password for bundle install: ")))
  (let ((default-directory (concat default-directory
                               "./fixtures/test-kitchen-mode-test-run/"))
    ;;; Added from accepted answer below by @sean
    ;;; need a buffer to display process in.
    (generated-buffer (generate-new-buffer "*test-kitchen-test-setup*")))
    (sudo-shell-command
      ;;; pass reference to generated process buffer by name.
      ;;; Need to add a defun to get the current test-kitchen buffer 
      ;;; if it exists to use, but that is outside the scope of the question.
      (buffer-name generated-buffer)
      password
      "bundle install; bundle exec berks install")
    (clear-string password)))

---

Say I need to call a process in elisp, and that process requires sudo priveleges. Example, running Ruby's bundle install:

(let ((generated-buffer (generate-new-buffer "*test-kitchen-test-setup*")))
  (display-buffer generated-buffer '((display-buffer . nil)) nil)
  (call-process-shell-command
    (concat "cd " (concat default-directory "./fixtures/test-kitchen-mode-test-run") 
            "; sudo bundle install; sudo bundle exec berks install;")
    nil generated-buffer t))

The bundle command requires sudo to install gems correctly. How can I call this shell command in elisp with sudo, enter the password, and still be able to display the results in the generated window?

Answer 1

Here's a helper function that executes a single shell command as sudo with a supplied password:

(defun sudo-shell-command (buffer password command)
  (let ((proc (start-process-shell-command
               "*sudo*"
               buffer
               (concat "sudo bash -c "
                       (shell-quote-argument command)))))
    (process-send-string proc password)
    (process-send-string proc "\r")
    (process-send-eof proc)))

You might apply it to your situation like so:

(defun sudo-bundle-install (password)
  (interactive (list (read-passwd "Sudo password for bundle install: ")))
  (let ((default-directory (concat default-directory
                                   "./fixtures/test-kitchen-mode-test-run/")))
    (sudo-shell-command
     "*test-kitchen-test-setup*"
     password
     "bundle install; bundle exec berks install")
    (clear-string password)))

Answer 2

You need to create a file with your password:

(defun my-run-command-under-sudo (password command &rest cpsc-args)
  "Run COMMAND under sudo with your PASSWORD.
Other arguments are passed to `call-process-shell-command'
 and should start with BUFFER (the output destination).
NB: this is _not_ secure: it creates a temp file with your password."
  (let ((password-file (make-temp-file "elisp-sudo")))
    (with-temp-file password-file (insert password))
    (unwind-protect
         (apply 'call-process-shell-command
                (concat "sudo " command)
                password-file cpsc-args)
      (delete-file password-file))))

Now you can do:

(let ((default-directory (concat default-directory "./fixtures/test-kitchen-mode-test-run")))
  (my-run-command-under-sudo "my-password" "bundle install" t)
  (my-run-command-under-sudo "my-password" "bundle exec berks install" t))