Question

I want to run sort-lines command on the whole file.

C-xhM-xsort-linesEnter

I need to mark the region before running sort-lines command.

How to skip the C-xh. Can I provide a argument (like % in vim) to sort-lines command?

Answer 1

Here’s what appears to be the simplest solution — if no region is active, pass the extents of the buffer to sort-lines:

(defun my-sort-lines (reverse begin end)
  (interactive "P\nr")
  (sort-lines reverse
              (if (region-active-p) begin (point-min))
              (if (region-active-p) end (point-max))))