OpenTTD has the option to run one of a number of scripts when it starts up.

The scripts should comprise a regular text file that's been renamed to whatever is relevent (see below). They should be put into the "scripts" directory in your OTTD install.

Local Scripts

autoexec.scr - This Script is executed on gamestart [all - use this for custom aliases per ex.]

Network Scripts

on_client.scr - This Script is executed whenever you join a server

on_server_connect.scr - This script will be executed by the server whenever a client connects (useful for motd)

These scripts should be used to set the servers port/ip and/or server optimization settings/patches.

pre_server.scr is executed before the servers tcp stack is started - in-game server only.

pre_dedicated.scr is executed before the servers tcp stack is started - Dedicated server only.

These network scripts should be used to set the servers name, password and so on.

on_server.scr is executed after starting a server - Both dedicated and in-game servers.

on_dedicated.scr is additionally executed after starting a server - dedicated serveronly.

game_start.scr is additionally executed after starting a game, If you want to start_ai in a dedicated server, config it here.