gamepad-launcher

A simple way to launch an application when a gamepad connects

Overview

Note: as it currently exists, this is written for and only tested on a particular Debian 11 system. It may or may not work on others without modification.

There are three components:

• a udev rule
  • The udev rule triggers when a device mapped to /dev/input/js0 is added to the system.
  • It attempts to start a systemd user unit called gamepad_launcher.service when triggered.
• the main systemd service unit
  • The systemd service is intended to be run by a systemd user instance.
  • If xow (github.com/medusalix/xow) is installed and the user has permissions (see below), it will be restarted when the service stops to turn off controllers.
  • Otherwise, this service doesn't do anything - it's meant for other services to attach onto and start with.
• a set of systemd service units for common applications
  • These service are also intended to be run by a systemd user instance.
  • If the desired application isn't included, an existing service file can be used as a template.
  • The desired service must be enabled manually during installation. Only one service can be enabled at a time; there are no checks to prevent collisions.

Application service files provided

• steam_bigpicture.service for "natively"-installed Steam.
• steam_bigpicture.flatpak.service for Flatpak-installed Steam.
• steam_bigpicture.flatpak.peruser.service for Flatpak per-user-installed Steam (flatpak --user install ...).
• steamlink.service for "natively"-install SteamLink (I think this is only applicable to Raspberry Pis).
• steamlink.flatpak.service for Flatpak-installed SteamLink.
• steamlink.flatpak.peruser.service for Flatpak per-user-install SteamLink (flatpak --user install ...).

Installation

Manual installation is as follows:

$ mkdir -p ~/.config/systemd/user
$ cp systemd/* ~/.config/systemd/user/
$ systemctl --user enable <selected_application_service.service>
$ systemctl --user daemon-reload
# cp udev/99-gamepads.rules /etc/udev/rules.d/
# udevadm control --reload

Automatically turning off controllers with xow

Restarting the xow service, if used (to connect Xbox One / Series controllers to the USB wireless dongle), should turn the controllers off. However, restarting the service normally requires root permissions. To get around this, a NOPASSWD line can be added to the sudoers file (or an included file in the appropriate directory). The recommended way is to run sudo visudo /etc/sudoers.d/gamepads and add the following line:

%video ALL = (root) NOPASSWD: /usr/bin/systemctl restart xow

and then any user who is a member of the group "video" should be able to restart xow without a password. Explaining why the visudo command should be used is outside the scope of this README; just know that you risk seriously screwing up your system if you don't.