Instance Layout

An instance is a directory with mc.toml at its root. All mc commands run from that directory, and everything the instance needs lives under it:

myserver/
├── mc.toml
├── mc.lock
├── .java/
├── .minecraft/
├── backups/
├── instance/
│   ├── eula.txt
│   ├── server.properties
│   ├── mods/
│   └── myserver/
└── temp/

Only one running server is allowed per instance directory; a second mc run in the same directory refuses to start.

mc.toml

The manifest describing the instance — the only file you author. See The Manifest Format.

mc.lock

The mod lockfile: the fully resolved set of mods, including required dependencies, that the instance last started with. Regenerated when the instance starts.

.java/ and .minecraft/

Installed Java runtimes and Minecraft binaries, keyed by version, shared by every start of this instance. Safe to delete while the instance is stopped; whatever is missing is downloaded again on the next start.

backups/

The default destination for backup archives when local storage is used. The directory is dedicated to this instance's backups; see Backups.

instance/

The live working directory of the Minecraft process. Notable contents:

  • eula.txt — generated from the eula key in the manifest.
  • server.properties — generated from the manifest on every start; manual edits are overwritten. Use the [server.properties] section of mc.toml instead. When the file holds secrets, such as an RCON password, mc creates it readable only by the owning user and refuses to start if its permissions have been loosened.
  • mods/ — the installed mods. This directory is fully managed: mc adds and removes jars to match the lockfile, so a jar placed here by hand is deleted on the next start. Declare URL mods in the manifest instead.
  • myserver/ — the world, named after the instance's name. Everything else Minecraft writes at runtime (logs, player data, allow list, and so on) also lives here and is left untouched by mc.

temp/

Scratch space for in-flight downloads and archives. Cleared when the instance starts; safe to delete while nothing is running.