Mark Line & Marking Transient Command

Emacs has a lot of commands for marking (selecting) things. You can find them all by typing M-x mark- and seeing the available options. You can also read about (most of) them in the manual. They all work the same way, they leave the point where it is and extend the region (selection) forward by a given about (word, sentence, etc) by moving the "mark" (end of region).

One command that is missing (no idea why) is one for marking lines. Fortunately, the code for mark-end-of-sentence is really simple and easily adapted to mark lines.

(defun mark-line (arg)
  "Put mark at end of line.
ARG works as in `forward-line'.  If this command is repeated,
it marks the next ARG lines after the ones already marked."
  (interactive "p")
     (if (and (eq last-command this-command) (mark t))
     (goto-char (mark)))
     (forward-line arg)
   nil t))

Additionally I have mark-end-of-sentence aliased to mark-sentence to be more consistent with the other mark commands.

I have also found it valuable to create a far more logical set of bindings for all these commands. I use the transient package for this, but you could set this up with a prefix binding or using another method you prefer.

(transient-define-prefix general-transient--mark ()
  "Transient for setting the mark."
  :transient-suffix 'transient--do-stay
  :transient-non-suffix 'transient--do-exit
   [("w" "Word" mark-word)
    ("s" "Sexp" mark-sexp)
    ("d" "Defun" mark-defun)]
   [("n" "Line" mark-line)
    (")" "Sentence" mark-sentence)
    ("}" "Paragraph" mark-paragraph)]
   [("<" "Beginning of Buffer" mark-beginning-of-buffer)
    (">" "End of Buffer" mark-end-of-buffer)]
   [("x" "Exchange Point/Mark" exchange-point-and-mark :transient nil)
    ("q" "Quit" transient-quit-all)]])