launch Command

Launch your Minecraft instance directly from the command line.

📝 Synopsis

clicraft launch [options]

📖 Description

The launch command starts your Minecraft instance with all the correct Java arguments, libraries, and configurations. It handles:

Java classpath setup
Native library extraction
JVM arguments configuration
Game arguments setup
Authentication (online mode)
Offline mode support

🎯 Options

Option	Description	Default
`-i, --instance <path>`	Path to instance directory	Current directory
`--offline`	Launch in offline mode (no authentication)	false
`--verbose`	Show detailed launch information	false

📋 Examples

Launch from instance directory

cd my-instance
clicraft launch

Launch with instance path

clicraft launch --instance ./my-instance

Launch in offline mode

clicraft launch --offline

No authentication required - useful for testing or single-player.

Verbose launch

clicraft launch --verbose

See detailed Java command and debugging information.

Launch specific instance

clicraft launch --instance ~/minecraft/modded-fabric

🎮 Example Session

Online Mode (Default)

$ cd my-instance
$ clicraft launch

Preparing to launch Minecraft...
✓ Instance detected: my-modded-world
✓ Minecraft version: 1.21.1
✓ Mod loader: Fabric 0.16.5
✓ Authentication: Player123
✓ Mods found: 5

Launching Minecraft...
[Minecraft window opens]

Offline Mode

$ clicraft launch --offline

Preparing to launch Minecraft...
✓ Instance detected: my-instance
✓ Minecraft version: 1.21.1
✓ Mod loader: Fabric 0.16.5
✓ Mode: Offline
✓ Username: Player

Launching Minecraft...
[Minecraft window opens]

🔍 Launch Process

What Happens

Instance Detection: Finds and validates mcconfig.json
Authentication Check: Verifies login status (unless --offline)
Library Preparation: Prepares Java libraries and native files
JVM Setup: Configures Java Virtual Machine arguments
Game Launch: Executes Java with Minecraft
Monitor: Keeps running to show game output

Verbose Output

With --verbose, you’ll see:

$ clicraft launch --verbose

Instance: ./my-instance
Minecraft Version: 1.21.1
Loader: fabric-loader-0.16.5-1.21.1
Authentication: Player123 (uuid: 123e...)

Java Command:
java -Xmx2G -Xms2G \
  -Djava.library.path=./natives \
  -cp ./libraries/*.jar:./versions/1.21.1.jar \
  net.fabricmc.loader.impl.launch.knot.KnotClient \
  --username Player123 \
  --uuid 123e4567... \
  --accessToken xxx \
  --version 1.21.1

[Game output follows]

🎯 Use Cases

Regular Gameplay

# Login first (one-time)
clicraft login

# Launch whenever you want to play
cd my-instance
clicraft launch

Testing Mods Offline

# Install mods
clicraft install sodium
clicraft install lithium

# Test in offline mode
clicraft launch --offline

Multiple Instances

# Launch different instances
clicraft launch --instance ./vanilla
clicraft launch --instance ./modded
clicraft launch --instance ./testing

Server Launch

cd my-server-instance
clicraft launch

# Server starts and runs in the terminal

Development Testing

# Quick offline testing
clicraft install my-mod --force
clicraft launch --offline --verbose

🖥️ System Requirements

Java

Required: Java 21 or higher
Recommended: Latest Java version
Memory: At least 4GB RAM available

Verify Java:

java --version

Display (Client Only)

Graphics drivers installed
Display server running (X11/Wayland on Linux)
Monitor connected

⚙️ Configuration

Launch behavior is configured in mcconfig.json:

{
  "name": "my-instance",
  "type": "client",
  "minecraftVersion": "1.21.1",
  "loader": "fabric",
  "loaderVersion": "0.16.5",
  "javaPath": "java",
  "jvmArgs": ["-Xmx2G", "-Xms2G"]
}

Customizing JVM Arguments

Edit mcconfig.json to customize Java settings:

{
  "jvmArgs": [
    "-Xmx4G",           // Maximum memory (4GB)
    "-Xms4G",           // Initial memory (4GB)
    "-XX:+UseG1GC",     // Use G1 garbage collector
    "-XX:+UnlockExperimentalVMOptions",
    "-XX:G1NewSizePercent=20",
    "-XX:G1ReservePercent=20",
    "-XX:MaxGCPauseMillis=50",
    "-XX:G1HeapRegionSize=32M"
  ]
}

Memory Recommendations

Instance Type	Recommended Memory
Vanilla	2GB (`-Xmx2G`)
Light mods	3GB (`-Xmx3G`)
Heavy mods	4-6GB (`-Xmx4G`)
Modpacks	6-8GB (`-Xmx6G`)
Servers	4-8GB+ depending on players

🌐 Online vs Offline

Online Mode (Default)

Requires clicraft login:

✅ Multiplayer servers
✅ Realms
✅ Custom skins
✅ Official servers
✅ Account verification

Offline Mode (`--offline`)

No login required:

✅ Single-player
✅ LAN play
✅ Mod testing
❌ Online multiplayer
❌ Custom skins
❌ Realms

📊 Game Output

The command shows Minecraft’s output:

[00:00:01] [main/INFO]: Loading Minecraft 1.21.1 with Fabric Loader 0.16.5
[00:00:02] [main/INFO]: Loading 5 mods
[00:00:02] [main/INFO]:   - sodium 0.6.0
[00:00:02] [main/INFO]:   - lithium 0.12.0
[00:00:03] [main/INFO]: Minecraft loaded successfully

Exit codes:

0 - Normal exit
1 - Crash or error
130 - Terminated by user (Ctrl+C)

⚠️ Common Issues

“Instance not found”

Make sure you’re in an instance directory or using --instance:

# Check for mcconfig.json
ls mcconfig.json

# Or specify instance
clicraft launch --instance ./my-instance

“Not logged in”

clicraft login
clicraft launch

Or use offline mode:

clicraft launch --offline

“Java not found”

Install Java 21 or higher:

# Verify Java installation
java --version

# If not installed, download from:
# https://adoptium.net/

“Out of memory”

Increase memory allocation in mcconfig.json:

{
  "jvmArgs": ["-Xmx4G", "-Xms4G"]
}

“Native library error”

On Linux, you may need:

sudo apt-get install libglfw3 libglfw3-dev

Game Crashes

Check the logs:

cd my-instance
ls logs/
cat logs/latest.log

🎮 Server Hosting

Starting a Server

cd my-server-instance
clicraft launch

# Server starts and shows:
[Server] Starting Minecraft server on *:25565
[Server] Done! Server is running

Server Commands

Type commands in the terminal:

> stop          # Stop the server
> list          # List players
> op username   # Make someone an operator

Background Server

Run server in background:

nohup clicraft launch > server.log 2>&1 &

View logs:

tail -f server.log

Stop server:

# Type 'stop' in server console or:
kill $(pgrep -f "minecraft.*server")

💡 Pro Tips

Login Once: Authentication persists, no need to login every launch
Check Status: Use clicraft status before launching
Test Offline: Use --offline for quick mod testing
Allocate Memory: Give Minecraft enough RAM for smooth gameplay
Close Other Apps: Close memory-heavy apps before launching
Use Verbose: Use --verbose for troubleshooting launch issues
Multiple Instances: Launch different instances for different play styles

🔧 Performance Tips

Optimize JVM Arguments

{
  "jvmArgs": [
    "-Xmx4G",
    "-Xms4G",
    "-XX:+UseG1GC",
    "-XX:+UnlockExperimentalVMOptions",
    "-XX:G1NewSizePercent=20",
    "-XX:G1ReservePercent=20",
    "-XX:MaxGCPauseMillis=50"
  ]
}

Install Performance Mods

clicraft install sodium      # Rendering
clicraft install lithium     # General
clicraft install starlight   # Lighting
clicraft install ferritecore # Memory

Monitor Performance

Use --verbose to see Java command and diagnose issues.

clicraft create - Create an instance to launch
clicraft login - Login for online play
clicraft install - Install mods before launching
clicraft info - View instance information

🔗 See Also

← Back to Commands

Next: info →

launch Command

📝 Synopsis

📖 Description

🎯 Options

📋 Examples

Launch from instance directory

Launch with instance path

Launch in offline mode

Verbose launch

Launch specific instance

🎮 Example Session

Online Mode (Default)

Offline Mode

🔍 Launch Process

What Happens

Verbose Output

🎯 Use Cases

Regular Gameplay

Testing Mods Offline

Multiple Instances

Server Launch

Development Testing

🖥️ System Requirements

Java

Display (Client Only)

⚙️ Configuration

Customizing JVM Arguments

Memory Recommendations

🌐 Online vs Offline

Online Mode (Default)

Offline Mode (--offline)

📊 Game Output

⚠️ Common Issues

“Instance not found”

“Not logged in”

“Java not found”

“Out of memory”

“Native library error”

Game Crashes

🎮 Server Hosting

Starting a Server

Server Commands

Background Server

💡 Pro Tips

🔧 Performance Tips

Optimize JVM Arguments

Install Performance Mods

Monitor Performance

📚 Related Commands

🔗 See Also

Offline Mode (`--offline`)