systemd optional in postinst

DEBIAN/postinst

@@ -1,4 +1,6 @@
 #!/bin/bash
-systemctl enable key-mapper
-systemctl stop key-mapper
-systemctl start key-mapper
+if [ -d "/run/systemd/system/" ]; then
+  systemctl enable key-mapper
+  systemctl stop key-mapper
+  systemctl start key-mapper
+fi

keymapper/state.py

@@ -82,7 +82,7 @@ class SystemMapping:
 
         if USER != 'root':
             # write this stuff into the key-mapper config directory, because
-            # the systemd service needs to know the xmodmap list on boot.
+            # the systemd service won't know the user sessions xmodmap
             path = get_config_path(XMODMAP_FILENAME)
             touch(path)
             with open(path, 'w') as file:

readme/usage.md

@@ -91,7 +91,7 @@ an example autoload entry:
 ```
 
 `preset name` refers to `~/.config/key-mapper/presets/device name/preset name.json`.
-The device name can be found with `evtest`.
+The device name can be found with `sudo key-mapper-control --list-devices`.
 
 Anything that is relevant to presets can be overwritten in them as well.
 Here is an example configuration for preset "a" for the "gamepad" device:
@@ -130,7 +130,7 @@ running (or without sudo if your user has the appropriate permissions).
 
 ```bash
 key-mapper-control --command autoload
-key-mapper-control --list-devices
+sudo key-mapper-control --list-devices
 key-mapper-control --command stop --device "Razer Razer Naga Trinity"
 key-mapper-control --command start --device "Razer Razer Naga Trinity" --preset "~/.config/key-mapper/presets/gamepad/a.json"
 ```