a# Launch Args API A Fabric library that provides common hooks to access Minecraft launch arguments

Usage

CREATE_SPECS Event

Gives you access to joptsimple OptionParser object

PARSE_ARGS Event

Gives you access to joptsimple OptionSet object

public class LaunchArgsTest implements ArgsListener {
    private static final Logger LOG = LogUtils.getLogger();
    private OptionSpec<Void> optionSpec;

    @Override
    public void createSpecs(OptionParser optionParser) {
        optionSpec = optionParser.accepts("someArg");
    }

    @Override
    public void parseArgs(OptionSet optionSet) {
        if (optionSet.has(optionSpec)) LOG.info("Found argument!");
    }
}

repositories {
    maven {
        name = "meteor-maven"
        url = "https://maven.meteordev.org/releases"
    }
}

dependencies {
  modImplementation "io.github.racoondog:LaunchArgsAPI:1.1.3"
  include "io.github.racoondog:LaunchArgsAPI:1.1.3"
}

Difference between LaunchArgsAPI and FabricLoader.getLaunchArguments

Parsing custom launch arguments from FabricLoader.getLaunchArguments() doesn't remove the "Completely ignored arguments" message

Minecraft launch argument documentation

Since I couldn't find this anywhere else...

Client (As of 1.19.3)

• --demo: Enables demo mode if present
• --disableMultiplayer: Disables multiplayer if present
• --disableChat: Disables chat if present
• --fullscreen: Starts game in fullscreen if present
• --checkGlErrors
• --jfrProfile
• --server: String; Server address to join after game initialization
• --port: Integer; Server port to join after game initialization
• --gameDir: File; Defaults to .
• --assetsDir: File; Defaults to {gameDir}/assets/
• --resourcePackDir: File; Defaults to {gameDir}/resourcepacks/
• --proxyHost: String
• --proxyPort: Integer; Defaults to 8080
• --proxyUser: String
• --proxyPass: String
• --username: String; Defaults to Player {4 random digits}; Minecraft account username, required for login
• --uuid: String; Defaults to random; Minecraft account uuid, required for login
• --xuid: String; Defaults to empty; XBox uuid
• --clientId: String; Defaults to empty
• --accessToken: String; Required; Minecraft account token, required for login
• --version: String; Required
• --width: Integer; Defaults to 854
• --height: Integer; Defaults to 480
• --fullscreenWidth: Integer
• --fullscreenHeight: Integer
• --userProperties: String; Defaults to {}
• --profileProperties: String; Defaults to {}
• --assetIndex: String
• --userType: String; Defaults to legacy
• --versionType: String; Defaults to release

Server (As of 1.19.3)

• --nogui: Disables gui if present
• --initSettings: Initializes 'server.properties' and 'eula.txt', then quits
• --demo: Enables demo mode if present
• --bonusChest: Enables bonus chest if present
• --forceUpgrade: Forcibly runs datafixers on world if present
• --eraseCache: If present, erase cache (Heightmaps, Lightmaps) during world upgrade, only has an effect if forceUpgrade is present
• --safeMode: Loads level with vanilla datapack only if present
• --help: Prints commands, then quits
• --singleplayer: String
• --universe: String; Defaults to .
• --world: String
• --port: Integer; Defaults to -1
• --serverId: String
• --jfrProfile
• nogui: Disables gui if present

Thanks unascribed for helping me understand some launch arguments