The Startup tab shows the start command (read-only) and the variables it uses: version, jar file, server name, passwords, ports, mod IDs. Each game type has its own set; hover over a variable for its description.
How they work
Variables are environment variables inside your server's container. The start command references them (), the install script reads them (which version to download), and some eggs write them into config files on every start (Palworld's PalWorldSettings.ini, ARK's session name, 7 Days' password).
That last part matters: a value written by the egg on every start overrides what you put in the config file. Change those in Startup, not in the file.
Takes effect when
- Most variables: on the next restart.
- Version variables (Minecraft version, Forge/Fabric/NeoForge version, Steam branch): after Settings → Reinstall, because the files must be downloaded again.
- Docker image (Java/Node/Python version): next restart.
Validation
Each variable has rules (number range, allowed words). The panel refuses invalid values with a message (e.g. Valheim's password must be at least 5 characters).
Kowalski
Ask "set the server name to Pengu SMP and turn off BattlEye" and it changes the right variables and tells you if a reinstall is needed.