Emacs: Copy/Cut Current Line If No Selection

Here's a command to cut current line if there's no text selection.

(defun xah-cut-line-or-region ()
  "Cut current line, or text selection.
When `universal-argument' is called first, cut whole buffer (respects `narrow-to-region').

URL `http://ergoemacs.org/emacs/emacs_copy_cut_current_line.html'
Version 2015-06-10"
  (interactive)
  (if current-prefix-arg
      (progn ; not using kill-region because we don't want to include previous kill
        (kill-new (buffer-string))
        (delete-region (point-min) (point-max)))
    (progn (if (use-region-p)
               (kill-region (region-beginning) (region-end) t)
             (kill-region (line-beginning-position) (line-beginning-position 2))))))

Copy Line or Append Copy Line or Region

This command copy current line if there's no text selection. If called again, it'll append-copy next line. So you can press a key repeatedly to keep copying lines.

(defun xah-copy-line-or-region ()
  "Copy current line, or text selection.
When called repeatedly, append copy subsequent lines.
When `universal-argument' is called first, copy whole buffer (respects `narrow-to-region').

URL `http://ergoemacs.org/emacs/emacs_copy_cut_current_line.html'
Version 2018-09-10"
  (interactive)
  (if current-prefix-arg
      (progn
        (copy-region-as-kill (point-min) (point-max)))
    (if (use-region-p)
        (progn
          (copy-region-as-kill (region-beginning) (region-end)))
      (if (eq last-command this-command)
          (if (eobp)
              (progn )
            (progn
              (kill-append "\n" nil)
              (kill-append
               (buffer-substring-no-properties (line-beginning-position) (line-end-position))
               nil)
              (progn
                (end-of-line)
                (forward-char))))
        (if (eobp)
            (if (eq (char-before) 10 )
                (progn )
              (progn
                (copy-region-as-kill (line-beginning-position) (line-end-position))
                (end-of-line)))
          (progn
            (copy-region-as-kill (line-beginning-position) (line-end-position))
            (end-of-line)
            (forward-char)))))))

Put the code in your emacs init file.

You need to give them keys. [see Emacs: How to Define Keys] A great hand saver is to bind them to single keys. Like this:

(global-set-key (kbd "<f2>") 'xah-cut-line-or-region) ; cut
(global-set-key (kbd "<f3>") 'xah-copy-line-or-region) ; copy
(global-set-key (kbd "<f4>") 'yank) ; paste

This is now part of ergoemacs-mode and xah fly keys.

2010-05-21 The code was inspired from http://www.emacswiki.org/emacs/SlickCopy. Thanks to Joseph O'Donnell for mentioning it. Apparently, this behavior is default in VisualStudio, TextMate, Sublime Text, SlickEdit.