When learning about Gemini today, I clicked on a
gemini:// link, set my Firefox open-with preference to a command line client and clicked “Open link”, but nothing happened.
Searching for a way to launch a
.desktop by command line, hoping for better debugging experience, I got
gtk-launch <.desktop name>. With that name I assumed there was a GTK or GLib or G-something way to launch
.desktop and Firefox was likely also using it. Using that command, again, no new terminal was launched but at least there was a line by shell spawned by gtk-launch complaining xterm not found.
A quick search about how to set terminal to use with gtk-launch returned nothing but old and unanswered StackOverflow threads. Time to read the source. I’ve looked into GTK and GLib a little bit before, quite readable, so it should not be hard for me.
gtk/gtk-launch.c I found this:
if (!g_app_info_launch (info, l, launch_context, &error))
A G-something way, as I guessed.
g_app_info_launch brought me to GIO, a part of GLib. Within that function I saw this:
return (* iface->launch) (appinfo, files, launch_context, error);
GAppInfo was an interface and I needed to dig into the used implementation.
Back to gtk-launch, looking at what
info variable was:
info = G_APP_INFO (g_desktop_app_info_new (desktop_file_name));
GDesktopAppInfo it was.
In GDesktopAppInfo, digging into functions, I found out that it would use either
*_with_spawn one sounded simpler. Assuming those two ways would not differ to much in finding terminal emulators to use, I looked into that one and saw:
if (info->terminal && !prepend_terminal_to_vector (&argc, &argv))
prepend_terminal_to_vector was the routine for finding terminal emulators. It found within a few hard-coded names and fallback to
xterm . There were
dtterm and finally
xterm. The one I used was not on the list.
As I will likely not install xterm on my machine, I created an xterm link to my terminal and problem solved. gtk-launch and Firefox now launch command line tools successfully.