Minecraft Java Edition Server Launcher

PowerShell Auto‑Update & Launch Script

server.ps1 is a single‑file utility that installs Java (if missing), fetches the requested or latest minecraft_server-<version>.jar, accepts the EULA on your behalf (optional), and starts the server with sensible defaults—all on Windows via PowerShell.

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Features

• Java bootstrap – Installs OpenJDK 21 automatically through winget when no compatible Java runtime is found.
• Version‑aware download – Downloads the specified version or the latest release. The Mojang version manifest is queried only when the latest version is requested, avoiding unnecessary network calls.
• EULA automation – Pass -Eula yes|true to skip the interactive prompt and write eula=true to eula.txt.
• 16 GB heap & nogui by default – Tweakable with -MinMemory, -MaxMemory, and -Gui switches.
• Modular functions – Each major step lives in its own function for easy maintenance and reuse.

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Tested Environment

Item	Recommended / Required
OS	Windows 10 / 11
Shell	PowerShell 7.x or Windows PowerShell 5.1
Package manager	winget (bundled with Windows App Installer)
Network	HTTPS access to launchermeta.mojang.com

Heads‑up: If winget is unavailable, pre‑install Java 21 and make sure it is on PATH.

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Quick Start

# Run from the script’s directory – grabs the latest build & auto‑accepts the EULA
./server.ps1 -Eula yes

First‑run flow:

1. Check for Java; install if missing.
2. Resolve the latest version and download the JAR if not present.
3. Ensure eula.txt exists and contains eula=true (auto or interactive).
4. Launch the server with the requested heap size.

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Parameters

Parameter	Type	Default	Description
-Version	string	latest	Example: "1.20.4" to pin a version.
-MinMemory	string	16G	Passed to Java as -Xms.
-MaxMemory	string	16G	Passed to Java as -Xmx.
-Gui	switch	off	Show the legacy server GUI instead of nogui.
-Eula	string	empty	yes or true = non‑interactive EULA acceptance.

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Usage Examples

Start a specific version with an 8 GB heap

./server.ps1 -Version 1.20.4 -MinMemory 8G -MaxMemory 8G -Eula yes

Start with the GUI enabled (4 GB heap)

./server.ps1 -MinMemory 4G -MaxMemory 4G -Gui -Eula yes

Grab the latest version and confirm the EULA interactively

./server.ps1

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About the EULA

Running a Minecraft server requires acceptance of the Mojang EULA. The script supports:

• -Eula yes|true – immediately writes eula=true.
• No -Eula flag – prompts for confirmation.

Read the full EULA here: https://aka.ms/MinecraftEULA.

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Java Installation Strategy

• Only triggers winget install Microsoft.OpenJDK.21 when Java is missing.
• Refreshes the current session’s PATH so the new Java is available right away.

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Script Layout (bird’s‑eye view)

server.ps1
├─ Install-Java       # Java presence check & winget install
├─ Get-Manifest       # Fetches version manifest (latest only)
├─ Ensure-ServerJar   # Verifies & downloads the server JAR
├─ Ensure-Eula        # Verifies & updates eula.txt
└─ Main               # Orchestrates steps & launches Java

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Caveats & Tips

• Backup your world—the script does not guard against map corruption.
• Future changes in Mojang’s API or download host can break the script.
• Linux/macOS are not supported; use a shell script or container solution instead.

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License

Licensed under the Apache License 2.0. See the LICENSE file for full text.

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Contributing

1. Open an issue or pull request.
2. When reporting bugs, include your PowerShell version, Windows build, and the exact command line you ran.

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Author

Satoru Yoshihara (Vaduz) @Vaduzjp