Notable Files/Folders

If you were after build instructions, check out the compile Batocera page. If you were after a more general introduction to contributing code to Batocera, check out the coding rules page. Think of this more as a cheat sheet after you've got to grips with the basics.

Batocera is a very complex project, and it's easy to get lost in all the files and directories of both the source code and the live install. If you're a new developer, or just curious about which file does what, this page is a short list of some important files and their purposes.

Emulator configuration files, including configuration generation. Batocera is a bit different from most static front-ends in that the configuration files for each emulator is generated upon the launch of the emulator, based on the settings the user has selected in EmulationStation (and by extension, /userdata/system/batocera.conf).

File purpose	Github source location	Final image location (x86_64)	Notes
Config generators (emulator defaults)	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/core/batocera-configgen/configgen/configgen/generators	/usr/lib/python#.#/site-packages/configgen/generators/	The infamous Python configuration generators, bane of the end-user who's used to modifying INI and XML files directly. These are what create the necessary configuration files, controller profiles and any other necessary INI/CFG file an emulator uses upon launching an emulator. Used in conjunction with ES advanced per-system options to make these generated configs based on the options the user has set in ES. If creating a new one, don't forget to define it as well.
Emulator launch command array generator	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/emulationstation/batocera-es-system/batocera-es-system.py	Generates /usr/share/emulationstation/es_systems.cfg and es_features.cfg	This one generates the run command (command array) that is written to /usr/share/emulationstation/es_systems.cfg in the final image.
Emulator config generator	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/core/batocera-configgen/configgen/configgen/generators followed by /<system name>/<system name>Generator.py	/usr/lib/python3.9/site-packages/configgen/generators/<system name>/<system name>Generator.py	The “main” generator script for an emulator. This is the file that is specified by the emulator launcher specifier. This script can be separated into multiple scripts that call upon each other to separate and better organize the code.
Emulator patches	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/emulators followed by /<emulator>	N/A, used during compiling the emulators at	Patches applied on top of the emulator binaries to make them work with Batocera.
EVMAPY keys files	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/emulators followed by /<emulator>/<system>.<emulator>.keys	/usr/share/evmapy/<system><emulator>.keys	These are the pad2key maps that assign the Hotkey + button shortcuts to emulators that only support shortcuts via keyboard presses (and also others too because why not). Commonly referred to by the emulator config generators when they are generating the controller configuration.
Global parameters	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-configgen/configs/configgen-defaults.yml	/usr/share/batocera/configgen/configgen-defaults.yml	The default global parameters that apply to all platforms. These configurations get applied first, followed by the architecture specific parameters. Only really used to select the default emulator for each system. Be careful, as if you select an emulator to be default that doesn't build on all platforms, compilation will fail. These have a lower priority than what the user has set in their batocera.conf.
Architecture parameters	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-configgen/configs/ followed by configgen-defaults-[architecture_name].yml	/usr/share/batocera/configgen/configgen-defaults-arch.yml	The default platform parameters. These are used to specify certain platform-specific default settings to be applied globally or per system. These have a lower priority than what the user has set in their batocera.conf and should only be used if a particular platform should use something different from the global parameters.
Emulator makefiles	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/emulators	N/A, only used in compiling Batocera	The makefiles that call upon the repos of the emulators included in Batocera and builds them into
Batocera Files (directories for emulators)	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-configgen/configgen/configgen/batoceraFiles.py		The paths used by emulators for their configuration files, saves, etc.
Shader sets	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/emulators/retroarch/shaders/batocera-shaders/configs	/usr/share/batocera/shaders/configs/	Contains some of the preset shader sets included with Batocera, the ones available in ES's menu.
The Bezel Project systems	https://github.com/batocera-linux/batocera.linux/blob/master/scripts/linux/thebezelproject/tbp_systems.txt		The list of all systems and their Bezel Project URL.

The options displayed in the main menus to the user.

Code related specifically to Batocera, not usually interchangeable with other distributions which use EmulationStation.

File purpose	Github source location	Final image location (x86_64)	Notes
Batocera user config template	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-system/batocera.conf	/userdata/system/batocera.conf	The main configuration file of Batocera. It's not actually necessary to have anything in the file, as Batocera can function without needing any pre-configuration, however you may want to keep it for certain pre-configured settings like enabled Bluetooth and Wi-Fi (remember, Batocera was initially designed for low-powered handhelds and SBCs so these were the old defaults back in the day).
Batocera boot template	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-system/batocera-boot.conf	/boot/batocera-boot.conf	Useful to look at this on the Github to see if any new keys/explanations have been added.
Batocera core directory	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/core	Various, though most are in /usr/bin/	Where most of Batocera's core functionalities are!
Batocera scripts	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/core/batocera-scripts/scripts	/usr/bin/	Where most bash scripts are! These are the files you're calling when you run commands via SSH or the terminal.
Emulator launcher specifier	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-configgen/configgen/configgen/emulatorlauncher.py	/usr/lib/python3.9/site-packages/configgen/emulatorlauncher.py	Defines which emulators use which config generators upon launching. If you've added a new standalone system, you'll need to define it here. Also defines what conditions are sent to custom user scripts triggered by batocera-emulationstation.
Config gen definitions	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-configgen/configgen/setup.py		This is where all the available config generators are defined. If you've added a new generator, you'll need to define it here. This is also where you'll find the “defaults” for many emulators.
ES systems	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/emulationstation/batocera-es-system/es_systems.yml	Recipe to /usr/share/emulationstation/es_features.cfg, and defines which packages they depend on	Source to the CFG file created for ES for its configured systems. This is the one you'll have to add a new entry to if you've added a new emulator/system to Batocera. Also contains the information used to generate the _info.txt files in the /userdata/roms/ directories. You can specify which platforms this emulator is included in with the included emulators config file.
Supplementary emulator files	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/emulationstation/batocera-es-system/roms		Extra files/folders required for the system.
Batocera es_system generator	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/emulationstation/batocera-es-system/batocera-es-system.py		Generates the es_systems.cfg file. Generates roms folder and emulators folders. Generate the _info.txt file with the emulator information. Information from the emulators are being extracted from the file es_system.yml
BIOS file database	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-scripts/scripts/batocera-systems		Catalogue of all the BIOS files for various emulators and their md5 checksums.
Batocera decorations generator	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-configgen/configgen/configgen/utils/bezels.py		Generates the composite image used as the overlay (decoration). Recently, most of this was in libretro's configgen, but recent developments have made this independent of libretro.
Compiled component configuration	https://github.com/batocera-linux/batocera.linux/blob/master/package/batocera/core/batocera-system/Config.in		This is where all the modules you want to compile with Batocera are specified. This can be used to exclude/include particular core utilities for certain platforms.
Batocera desktop shortcuts	https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/core/batocera-desktopapps	/usr/share/applications	The shortcuts shown in the "Applications" in the file manager's sidebar.
Case switch scripts	Various folders in https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/utils (most are in https://github.com/batocera-linux/batocera.linux/tree/master/package/batocera/utils/rpigpioswitch)	/usr/bin/	The various power devices and buttons that can be selected in batocera.conf

All the “pre-installed” stuff that comes with a fresh Batocera install. Certain Batocera-specific media are stored as a copy at the Batocera-assets Github.

These are the board/platform specific patches.