Create function open-this-file-as-other-user

It opens the current file as the specified user or root.

init.el

@@ -827,6 +827,7 @@
 (load "buf-manipulation.el")
 (load "text-manip")
 (load "frame-manip")
+(load "file-manip")
 
 ;; Define aliases
 (defalias 'yes-or-no-p 'y-or-n-p)

lisp/file-manip.el

@@ -0,0 +1,13 @@
+(defun open-this-file-as-other-user (user)
+  "Edit current file as USER, using `tramp' and `sudo'.  If the current
+buffer is not visiting a file, prompt for a file name."
+  (interactive "sEdit as user (default: root): ")
+  (when (string= "" user)
+    (setq user "root"))
+  (let* ((filename (or buffer-file-name
+                       (read-file-name (format "Find file (as %s): "
+                                               user))))
+         (tramp-path (concat (format "/sudo:%s@localhost:" user) filename)))
+    (if buffer-file-name
+        (find-alternate-file tramp-path)
+      (find-file tramp-path))))