Emacs support for --hyperlink in ls?

Emacs support for --hyperlink in ls?

[Stephen Eglen]

Various programs, including ls (GNU coreutils 9.0), now contain
--hyperlink flag and similar to markup file names with the full
file-path.  The full file name is embedded using 'OSC 8 escape sequence'
so that it can be hidden in terminal emualators and recognised as a hyperlink.

For a video example using the kitty terminal, see

https://download.calibre-ebook.com/videos/kitty.mp4

the relevant part starts about 3min in; several other terminals also
support this feature.  Further documentation of this feature is on the
following page

https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda

Should Emacs support these OSC 8 hyperlinks in things like *shell*?

If I run M-x shell, of course, these hyperlinks appear verbatim.

$ ls -1 --hyperlink /etc | head -5

%1b]8;;file://light/etc/acpi\aacpi%1b]8;;\a
%1b]8;;file://light/etc/adjtime\aadjtime%1b]8;;\a
%1b]8;;file://light/etc/alsa\aalsa%1b]8;;\a
%1b]8;;file://light/etc/anacrontab\aanacrontab%1b]8;;\a
%1b]8;;file://light/etc/ant.conf\aant.conf%1b]8;;\a

If people think it worth trying, I might start hacking something to work
e.g. on comint-output-filter-functions but presumably this might be
something that eshell, ansi-term and vterm might also benefit from?

Stephen

Re: Emacs support for --hyperlink in ls?

[Eli Zaretskii]

> From: Stephen Eglen <sje30@cam.ac.uk>
> Date: Tue, 03 May 2022 12:08:30 +0100
> 
> Various programs, including ls (GNU coreutils 9.0), now contain
> --hyperlink flag and similar to markup file names with the full
> file-path.  The full file name is embedded using 'OSC 8 escape sequence'
> so that it can be hidden in terminal emualators and recognised as a hyperlink.
> 
> For a video example using the kitty terminal, see
> 
> https://download.calibre-ebook.com/videos/kitty.mp4
> 
> the relevant part starts about 3min in; several other terminals also
> support this feature.  Further documentation of this feature is on the
> following page
> 
> https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
> 
> Should Emacs support these OSC 8 hyperlinks in things like *shell*?
> 
> If I run M-x shell, of course, these hyperlinks appear verbatim.
> 
> $ ls -1 --hyperlink /etc | head -5
> 
> %1b]8;;file://light/etc/acpi\aacpi%1b]8;;\a
> %1b]8;;file://light/etc/adjtime\aadjtime%1b]8;;\a
> %1b]8;;file://light/etc/alsa\aalsa%1b]8;;\a
> %1b]8;;file://light/etc/anacrontab\aanacrontab%1b]8;;\a
> %1b]8;;file://light/etc/ant.conf\aant.conf%1b]8;;\a
> 
> If people think it worth trying, I might start hacking something to work
> e.g. on comint-output-filter-functions but presumably this might be
> something that eshell, ansi-term and vterm might also benefit from?

comint.el already supports OSC 8, since Emacs 28.

Re: Emacs support for --hyperlink in ls?

[Stephen Eglen]

> comint.el already supports OSC 8, since Emacs 28.

Thank you!  I should have checked NEWS closer.

I have added this:

(add-to-list 'comint-output-filter-functions 'comint-osc-process-output)

and confirm that in *shell* the filenames are now hyperlinks.

However, at least on my system, I find the following problem that I
think is caused by ls, rather than Emacs.  e.g.

$ ls --hyperlink /etc/anacrontab

generates the following filename (after removing the markup)

file://light/etc/anacrontab

where 'light' is the name of my laptop (running arch linux).
browse-url-xdg-open is my browser-function, and

$ xdg-open file://light/etc/anacrontab

generates the error:

xdg-open: file 'file://light/etc/anacrontab' does not exist

I have made a temporary workaround by adapting the following function to
remove the hostname if it matches (system-name) which seems to solve the
problem for me in initial testing, so that e.g. the URL becomes
file:///etc/anacrontab

(defun comint-osc-hyperlink-handler (_ text)
  "Create a hyperlink from an OSC 8 escape sequence.
This function is intended to be included as an entry of
`comint-osc-handlers'."
  (when comint-osc-hyperlink--state
    (let ((start (car comint-osc-hyperlink--state))
          (url (cdr comint-osc-hyperlink--state)))
      (make-text-button start (point)
                        'type 'comint-osc-hyperlink
                        'browse-url-data url)))
  (setq comint-osc-hyperlink--state
        (and (string-match ";\\(.+\\)" text)
             (cons (point-marker) (match-string-no-properties 1 text))))
  (let* ( (url (url-generic-parse-url (cdr comint-osc-hyperlink--state)))
	  (host (url-host url)))
    (when (equal (system-name) host)
      (setq comint-osc-hyperlink--state
	    (cons
	     (car comint-osc-hyperlink--state)
	     (concat "file://" (url-filename url)))))))

However, is this the correct approach?  (I note that a similar issue was
filed for kitty terminal, which also resulted in kitty being patched in
a similar fashion: https://github.com/kovidgoyal/kitty/issues/2970 so at
least it is not just my system. The 'foot' terminal also does not parse
urls with hostname that is not FQDN.)

Stephen

Re: Emacs support for --hyperlink in ls?

[Eli Zaretskii]

> From: Stephen Eglen <sje30@cam.ac.uk>
> Cc: Stephen Eglen <sje30@cam.ac.uk>, emacs-devel@gnu.org
> Date: Tue, 03 May 2022 21:38:47 +0100
> 
> However, at least on my system, I find the following problem that I
> think is caused by ls, rather than Emacs.  e.g.
> 
> $ ls --hyperlink /etc/anacrontab
> 
> generates the following filename (after removing the markup)
> 
> file://light/etc/anacrontab
> 
> where 'light' is the name of my laptop (running arch linux).
> browse-url-xdg-open is my browser-function, and
> 
> $ xdg-open file://light/etc/anacrontab
> 
> generates the error:
> 
> xdg-open: file 'file://light/etc/anacrontab' does not exist
> 
> I have made a temporary workaround by adapting the following function to
> remove the hostname if it matches (system-name) which seems to solve the
> problem for me in initial testing, so that e.g. the URL becomes
> file:///etc/anacrontab
> 
> (defun comint-osc-hyperlink-handler (_ text)
>   "Create a hyperlink from an OSC 8 escape sequence.
> This function is intended to be included as an entry of
> `comint-osc-handlers'."
>   (when comint-osc-hyperlink--state
>     (let ((start (car comint-osc-hyperlink--state))
>           (url (cdr comint-osc-hyperlink--state)))
>       (make-text-button start (point)
>                         'type 'comint-osc-hyperlink
>                         'browse-url-data url)))
>   (setq comint-osc-hyperlink--state
>         (and (string-match ";\\(.+\\)" text)
>              (cons (point-marker) (match-string-no-properties 1 text))))
>   (let* ( (url (url-generic-parse-url (cdr comint-osc-hyperlink--state)))
> 	  (host (url-host url)))
>     (when (equal (system-name) host)
>       (setq comint-osc-hyperlink--state
> 	    (cons
> 	     (car comint-osc-hyperlink--state)
> 	     (concat "file://" (url-filename url)))))))
> 
> However, is this the correct approach?  (I note that a similar issue was
> filed for kitty terminal, which also resulted in kitty being patched in
> a similar fashion: https://github.com/kovidgoyal/kitty/issues/2970 so at
> least it is not just my system. The 'foot' terminal also does not parse
> urls with hostname that is not FQDN.)

I think TRT is to report this to the Coreutils developers as a bug in
GNU 'ls'.

Re: Emacs support for --hyperlink in ls?

[Augusto Stoffel]

On Wed,  4 May 2022 at 08:48, Eli Zaretskii <eliz@gnu.org> wrote:

>> From: Stephen Eglen <sje30@cam.ac.uk>
>> Cc: Stephen Eglen <sje30@cam.ac.uk>, emacs-devel@gnu.org
>> Date: Tue, 03 May 2022 21:38:47 +0100
>> 
>> However, at least on my system, I find the following problem that I
>> think is caused by ls, rather than Emacs.  e.g.
>> 
>> $ ls --hyperlink /etc/anacrontab
>> 
>> generates the following filename (after removing the markup)
>> 
>> file://light/etc/anacrontab
>> 
>> where 'light' is the name of my laptop (running arch linux).
>> browse-url-xdg-open is my browser-function, and
>> 
>> $ xdg-open file://light/etc/anacrontab
>> 
>> generates the error:
>> 
>> xdg-open: file 'file://light/etc/anacrontab' does not exist
>
> I think TRT is to report this to the Coreutils developers as a bug in
> GNU 'ls'.

I think ls is doing TRT.  One may call 'ls --hyperlink' on a remote
machine, so a complete file URL is needed.

On my computer (running Fedora), xdg-open opens the file as expected.
So I suppose this is an issue in the OP's operating system.