Command-Line Arguments

Control Prism Launcher behavior and launch instances directly from the command line

Prism Launcher provides extensive command-line interface (CLI) support for automation, scripting, and advanced workflows.

Synopsis

prismlauncher [OPTIONS] [URL...]

Basic Options

Help and Version

--help · flag · default: "false"

Display help text and exit

prismlauncher --help

--version · flag · default: "false"

Display program version and exit

prismlauncher --version

Shows the launcher version, Git commit hash, and build information.

Data Directory

--dir · string

-d · string

Use a custom directory as the application root

Linux/macOS

prismlauncher --dir /path/to/data

Windows

prismlauncher.exe --dir "C:\PrismData"

Special value:

Use current directory

prismlauncher --dir .

This overrides the PRISMLAUNCHER_DATA_DIR environment variable and the default data directory location.

Instance Management

Launching Instances

--launch · string

-l · string

Launch the specified instance by its ID

prismlauncher --launch "MyInstance"

The instance ID is typically the folder name in your instances directory.

The launcher window will open and the instance will start automatically. Use with --server or --world to join specific servers or worlds.

--show · string

Open the window for the specified instance without launching it

prismlauncher --show "MyInstance"

This opens the instance window, allowing you to configure settings before launch.

Launch Modifiers

These options modify how instances are launched and must be used in combination with --launch.

--server · string

-s · string

Join the specified server on launch

prismlauncher --launch "MyInstance" --server "mc.hypixel.net"

For servers with custom ports:

prismlauncher --launch "MyInstance" --server "example.com:25565"

Only valid in combination with --launch. Using without --launch will result in an error.

--world · string

-w · string

Join the specified world on launch (singleplayer)

prismlauncher --launch "MyInstance" --world "My Survival World"

The world name must match exactly as it appears in the saves folder.

Requires Minecraft 1.20+ with quick play support. Only valid with --launch.

Account Selection

--profile · string

-a · string

Use the account specified by its profile name

prismlauncher --launch "MyInstance" --profile "PlayerName"

The profile name is shown in the Accounts page of the launcher.

Only valid in combination with --launch.

--offline · string

-o · string

Launch in offline mode with the specified player name

prismlauncher --launch "MyInstance" --offline "Steve"

This bypasses authentication and launches without a valid account. Only valid with --launch.

Resource Import

--import · string

-I · string

Import instance or resource from specified local path or URL

Local file

prismlauncher --import "/path/to/modpack.zip"

URL

prismlauncher --import "https://example.com/modpack.mrpack"

Multiple imports

prismlauncher --import "pack1.zip" --import "pack2.mrpack"

Supported formats:

• .mrpack - Modrinth modpacks
• .zip - CurseForge, ATLauncher, Technic modpacks
• Modrinth URLs
• CurseForge URLs

Positional URL Arguments

You can also specify URLs as positional arguments (equivalent to --import):

prismlauncher "https://modrinth.com/modpack/example"

Multiple URLs

prismlauncher "url1" "url2" "url3"

Utility Options

--alive · flag · default: "false"

Write a small live.check file after the launcher starts

prismlauncher --alive

This creates a file that can be used by external scripts to verify the launcher started successfully.

The file location is in the data directory and contains the application ID.

Complete Examples

Basic Launch Scenarios

Launch specific instance

prismlauncher --launch "FTB Infinity Evolved"

Advanced Workflows

Custom data directory and launch

prismlauncher --dir "/mnt/games/minecraft" --launch "Survival"

Automation Scripts

Linux: Launch script with logging

#!/bin/bash
LOG_FILE="$HOME/minecraft-launch.log"
echo "[$(date)] Launching instance" >> "$LOG_FILE"
prismlauncher --launch "MyInstance" >> "$LOG_FILE" 2>&1

Desktop Shortcuts

Create desktop shortcuts for quick instance launching:

Linux .desktop file

[Desktop Entry]
Type=Application
Name=Launch Minecraft Server
Exec=prismlauncher --launch "ServerInstance" --server "mc.example.com"
Icon=prismlauncher
Terminal=false
Categories=Game;

Error Handling

Exit Codes

0 · exit code

Success - Launcher started or command completed successfully

1 · exit code

Failure - Syntax error, configuration error, or unexpected error

Common causes:

• Invalid command-line arguments
• Instance not found
• Data directory inaccessible
• Missing required options (e.g., --server without --launch)

Common Errors

Error: Options require --launch

--server, --profile and --offline can only be used in combination with --launch!

Instance Communication

When a Prism Launcher instance is already running:

1. New commands are forwarded to the existing instance
2. The new process exits after forwarding the command
3. The existing launcher window handles the request

This allows:

• Launching multiple instances from scripts
• Importing resources while launcher is open
• Remote control via command-line

Example: Import while launcher is running

# Launcher is already open
prismlauncher --import "newmodpack.mrpack"
# Command is forwarded, import dialog appears in existing window

Platform-Specific Notes

Linux AppImage

When running from AppImage:

./PrismLauncher.AppImage --launch "MyInstance"

The $APPIMAGE environment variable is automatically set and used for updates.

Windows Portable

For portable installations:

prismlauncher.exe --dir "."

Or create a portable.txt file in the launcher directory.

macOS Bundle

Access the binary inside the app bundle:

/Applications/Prism\ Launcher.app/Contents/MacOS/prismlauncher --launch "Instance"

Or use open:

open -a "Prism Launcher" --args --launch "MyInstance"

Integration Examples

Game Server Management

Launch on server start

#!/bin/bash
# server-start.sh
prismlauncher --launch "AdminClient" --server "localhost:25565" &
./start-minecraft-server.sh

Mod Testing Workflow

#!/bin/bash
# test-mod.sh
MOD_FILE="$1"
TEST_INSTANCE="ModTesting"

# Copy mod to instance
cp "$MOD_FILE" "$HOME/.local/share/PrismLauncher/instances/$TEST_INSTANCE/minecraft/mods/"

# Launch instance
prismlauncher --launch "$TEST_INSTANCE"

Automated Modpack Updates

#!/bin/bash
# update-modpacks.sh
for pack in pack1.mrpack pack2.mrpack pack3.mrpack; do
    echo "Importing $pack..."
    prismlauncher --import "$pack"
    sleep 2
done

Debugging

Enable verbose logging:

Linux/macOS

export QT_LOGGING_RULES="*.debug=true"
prismlauncher --launch "MyInstance"

Windows

$env:QT_LOGGING_RULES="*.debug=true"
prismlauncher.exe --launch "MyInstance"

Limitations

• Interactive operations (like account login) cannot be automated via CLI
• Instance names with spaces must be quoted
• Some operations require the GUI (e.g., initial setup wizard)
• World names must match exactly (case-sensitive)

Related Documentation

• Custom Commands - Automate tasks with pre/post-launch commands
• Environment Variables - Control launcher with environment variables
• Portable Mode - Use --dir for portable installations