Weekly Yak Shaving

Ahoy Emacs aficionados.

I don't know if it's a common experience to other Emacs' users, but often in my daily usage of the programmable editor, I became aware of a missing feature, I take a mental note that I should look into it later and usually I end up forgetting about it.

Rinse and repeat, but this time with a slightly sense of deja-vu.

Anywho, a few days ago, after a lot of postponement, I recalled that I wanted to expose the X's primary selection via a keyboard shortcuts on Emacs. For the non initiated, Xorg¹ traditionally uses two distinct buffers for copy/paste text operations: the "primary selection" and the "clipboard".

In Emacs, from what I know, the only way to paste the primary selection is clicking the middle mouse button. Well, hidden in the documentation there's the gui-get-primary-selection function, but strangely it doesn't work when invoked directly with a shortcut. It's not a big deal, but that's probably the reason why I wasn't bored enough to fix it yet.

So nothing earth shattering, it's only a wrapper and it's not going to increase my productivity tenfold, but it was a pet peeve of mine. For the interested reader:

;; paste X primary selection
(defun yank-primary-selection ()
  (interactive)
  (insert
   (gui-get-primary-selection)))

(global-set-key (kbd "C-c C-y") 'yank-primary-selection)

Unfortunately, outside Emacs there isn't a common easy way to access the primary selection without applying brittle hacks like, for example, simulating a middle mouse button click sending the corresponding X11 event and this ignoring Wayland² completely.

A little digression

I suppose for consistency with other desktops/operating systems, Shift-Insert is configured to paste the copy buffer and this is honored, I think, in all the applications I use, except for Gnome Terminal. In Gnome Terminal Shift-Insert paste the primary selection.

I tried in the past to add Shift-Insert to the default Control-Shift-v in the Gnome Terminal as a workaround, in other words having two shortcuts for the same action, but I doesn't seem to work. I tried to define an array with gsettings with the two bindings but only the first element of the array seems to be evaluated.

Bummer.

Another little digression

My default keyboard³ has a spare key in the top left corner, under the Esc key, so long time ago I mapped the "XF86Copy" and "XF86Paste" symbols to it. Unfortunately they aren't supported consistently on all applications as they work with Firefox for example, but I don't recall any Gnome or GTK based application where they do.

In Emacs I've added a couple of bindings, but I used to the traditional yank and kill⁴ shortcuts:

;; adding support for XF86Copy and XF86Paste
(global-set-key (kbd "<XF6Copy>") 'clipboard-kill-ring-save)
(global-set-key (kbd "<XF6Paste>") 'x-clipboard-yank)

To be honest, the configuration is there but I seldom use it.

The Shell

Now, for something slightly related, when using the shell and the result of a command is a single or at most a couple of lines, I can use it as an argument for another command using the following Zsh function instead to reach for the mouse to do a copy&paste:

# quote the last command to reuse output
_insert-last-command-output() {
    LBUFFER+="$(LS_COLORS= TERM=vt220 eval $history[$((HISTCMD-1))])"
}
zle -N _insert-last-command-output
bindkey '^[`' _insert-last-command-output

It's bound to Alt-` in my .zshrc and basically it relaunch the last executed command present in the shell history, with a couple of incantations used to remove colours from the output (a.k.a. ANSI escape sequences), and it injects it the Zsh input buffer. I don't recall where I "borrowed" the idea for the above function, but it has been handy plenty of times.

Finally, the Zsh copy-earlier-word is another pretty unknown little function that I've bound it to Alt-, that I want to throw to the interested reader. It treats the input buffer like a stack and pops out the current inserted words and it also works in the history parameters substitutions.

We should chalk it in the things Bash sorely misses.