PaperMC/src/main/java/org/bukkit/craftbukkit/Main.java

package org.bukkit.craftbukkit;

import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import joptsimple.OptionParser;
import joptsimple.OptionSet;
import net.minecraft.server.MinecraftServer;

public class Main {
    public static void main(String[] args) {
        // Todo: Installation script
        OptionParser parser = new OptionParser() {
            {
                acceptsAll(asList("?", "help"), "Show the help");

                acceptsAll(asList("c", "config"), "Properties file to use")
                        .withRequiredArg()
                        .ofType(File.class)
                        .defaultsTo(new File("server.properties"))
                        .describedAs("Properties file");

                acceptsAll(asList("P", "plugins"), "Plugin directory to use")
                        .withRequiredArg()
                        .ofType(File.class)
                        .defaultsTo(new File("plugins"))
                        .describedAs("Plugin directory");

                acceptsAll(asList("h", "host", "server-ip"), "Host to listen on")
                        .withRequiredArg()
                        .ofType(String.class)
                        .describedAs("Hostname or IP");

                acceptsAll(asList("w", "world", "level-name"), "World directory")
                        .withRequiredArg()
                        .ofType(String.class)
                        .describedAs("World dir");

                acceptsAll(asList("p", "port", "server-port"), "Port to listen on")
                        .withRequiredArg()
                        .ofType(Integer.class)
                        .describedAs("Port");

                acceptsAll(asList("o", "online-mode"), "Whether to use online authentication")
                        .withRequiredArg()
                        .ofType(Boolean.class)
                        .describedAs("Authentication");

                acceptsAll(asList("s", "size", "max-players"), "Maximum amount of players")
                        .withRequiredArg()
                        .ofType(Integer.class)
                        .describedAs("Server size");
            }
        };

        OptionSet options = null;

        try {
            options = parser.parse(args);
        } catch (joptsimple.OptionException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, ex.getLocalizedMessage());
        }

        if ((options == null) || (options.has("?"))) {
            try {
                parser.printHelpOn(System.out);
            } catch (IOException ex) {
                Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
            }
        } else {
            try {
                MinecraftServer.main(options);
            } catch (Throwable t) {
                t.printStackTrace();
            }
        }
    }

    private static List<String> asList(String... params) {
        return Arrays.asList(params);
    }
}