From 47db71fe3ea267086451d5f7a04edb1d2b72ea66 Mon Sep 17 00:00:00 2001
From: Daniel Langbein <daniel@systemli.org>
Date: Fri, 23 Feb 2024 13:54:03 +0100
Subject: [PATCH] docs: XDG mime types

---
 NixOS.md              | 55 +++++++++++++++++++++++++++++++++++++++++++
 modules/autostart.nix |  4 ----
 2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/NixOS.md b/NixOS.md
index 64cefe4..23a7bd3 100644
--- a/NixOS.md
+++ b/NixOS.md
@@ -31,6 +31,7 @@ This document contains general notes about NixOS that are independent of my NixO
   * [Run AppImages](#run-appimages)
   * [Audio troubleshooting - Realtek ALC898 Audio Codec on ASRock Z77 Extreme 4](#audio-troubleshooting---realtek-alc898-audio-codec-on-asrock-z77-extreme-4)
   * [Graphic drivers](#graphic-drivers)
+  * [XDG mimes, desktop files](#xdg-mimes-desktop-files)
   * [Additional resources](#additional-resources)
     * [Nix Pills](#nix-pills)
     * [Papers](#papers)
@@ -791,6 +792,60 @@ Configuration example to disable integrated GUP: See [./hosts/yodaGaming/configu
 
 Configuration example for an AMD GPU (https://github.com/tolgaerok/nixos-kde/blob/main/core/gpu/amd/default.nix): See [./modules/gpu-amd.nix](./modules/gpu-amd.nix)
 
+## XDG mimes, desktop files
+
+Desktop files:
+- `/run/current-system/sw/share/applications`
+- `/etc/profiles/per-user/yoda/share/applications/`
+
+Both above sub-paths are part of the `XDG_DATA_DIRS` variable:
+- `echo $XDG_DATA_DIRS | grep /run/current-system/sw/share`
+- `echo $XDG_DATA_DIRS | grep /etc/profiles/per-user/yoda/share`
+
+List default apps and the associated handlers:
+
+```shell
+handlr list
+```
+```console
+┌────────────────────────────────┬─────────────────────────────────────────┐
+│ application/octet-stream       │ thunderbird.desktop                     │
+│ ...                            │                                         │
+│ x-scheme-handler/sgnl          │ signal-desktop.desktop                  │
+└────────────────────────────────┴─────────────────────────────────────────┘
+```
+
+Set default handler for mime/extension:
+
+```shell
+handlr set text/html re.sonny.Junction.desktop
+```
+
+Open any URI with `handlr`:
+
+```shell
+handlr open https://wikipedia.org
+```
+
+Open any URI with `gio`, part of `glib`:
+
+```shell
+gio open https://wikipedia.org
+```
+
+- Note: `gio open` does not follow the XDG spec. https://discourse.nixos.org/t/configure-how-xdg-open-opens-html-files/6419/23
+
+Further examples:
+
+```shell
+xdg-settings get default-web-browser
+#=> re.sonny.Junction.desktop
+xdg-mime query default x-scheme-handler/http and x-scheme-handler/https
+#=> re.sonny.Junction.desktop
+xdg-mime query default text/html
+#=> firefox.desktop
+```
+
 ## Additional resources
 
 * Simple NixOS flake template for NixOS with HomeManager. https://github.com/Misterio77/nix-starter-configs#readme
diff --git a/modules/autostart.nix b/modules/autostart.nix
index 7f27ad9..98424e9 100644
--- a/modules/autostart.nix
+++ b/modules/autostart.nix
@@ -3,10 +3,6 @@
   # See also:
   #   Temporary workaround until https://github.com/nix-community/home-manager/issues/3447 is merged.
 
-  # Desktop files:
-  #   /run/current-system/sw/share/applications
-  #   /etc/profiles/per-user/yoda/share/applications/
-
   home-manager.users.yoda = { osConfig, config, pkgs, ... }: {
     home.file."keepassxc" = {
       target = ".config/autostart/org.keepassxc.KeePassXC.desktop";