[java] Launch Minecraft from command line - username and password as prefix

I'm trying to make a simple custom Minecraft launcher thing.

According to the Minecraft Wiki page for the Launcher, it should be possible to run the Minecraft launcher using username and password prefixes from the command line and go directly to the game instead of through the launcher.

I've tried various versions of java -cp -u=username -p=password minecraft.jar net.minecraft.LauncherFrame, and what it says is the old method:

java -cp minecraft.jar net.minecraft.LauncherFrame <username> <password>

The old method opens the minecraft launcher, just as if I double clicked the jar file, however it does not go directly to the menu screen.

The new way (using password and username as prefix), gives me an error message saying the prefix -u=username or -p=password don't exist.

Any help on this? I'm really stuck.

This answer is going to briefly explain how the native files are handled on the latest launcher.

As of 4/29/2017 the Minecraft launcher for Windows extracts all native files and places them info %APPDATA%\Local\Temp{random folder}. That folder is temporary and is deleted once the javaw.exe process finishes (when Minecraft is closed). The location of that temporary folder must be provided in the launch arguments as the value of

-Djava.library.path=

Also, the latest launcher (2.0.847) does not show you the launch arguments so if you need to check them yourself you can do so under the Task Manager (simply enable the Command Line tab and expand it) or by using the WMIC utility as explained here.

Hope this helps some people who are still interested in doing this in 2017.

For anyone meaning to do this more reliably for different Minecraft versions, I have a Python script (adapted from parts of minecraft-launcher-lib) that does the job very nicely

Besides setting some basic variables near the top after the functions, it calls a get_classpath that goes through for example ~/.minecraft/versions/1.16.5/1.16.5.json, and loops over the libraries array, checking to see if each object (within the array), is supposed to be added to the classpath (cp variable). whether this library is added to the java classpath is governed by the should_use_library function, deterministic based on the computer's architecture and operating system. finally, some jarfiles that are platform specific have extra things prepended to them (ex. natives-linux in org/lwjgl/lwjgl/3.2.1/lwjgl-3.2.1-natives-linux.jar). this extra prepended string is handled by get_natives_string and is empty if it doesn't apply to the current library

tested on Linux, distribution Arch Linux

#!/usr/bin/env python
import json
import os
import platform
from pathlib import Path
import subprocess


"""Debug output
"""
def debug(str):
    if os.getenv('DEBUG') != None:
        print(str)

"""
[Gets the natives_string toprepend to the jar if it exists. If there is nothing native specific, returns and empty string]
"""
def get_natives_string(lib):
    arch = ""
    if platform.architecture()[0] == "64bit":
        arch = "64"
    elif platform.architecture()[0] == "32bit":
        arch = "32"
    else:
        raise Exception("Architecture not supported")

    nativesFile=""
    if not "natives" in lib:
        return nativesFile

    # i've never seen ${arch}, but leave it in just in case
    if "windows" in lib["natives"] and platform.system() == 'Windows':
        nativesFile = lib["natives"]["windows"].replace("${arch}", arch)
    elif "osx" in lib["natives"] and platform.system() == 'Darwin':
        nativesFile = lib["natives"]["osx"].replace("${arch}", arch)
    elif "linux" in lib["natives"] and platform.system() == "Linux":
        nativesFile = lib["natives"]["linux"].replace("${arch}", arch)
    else:
        raise Exception("Platform not supported")

    return nativesFile


"""[Parses "rule" subpropery of library object, testing to see if should be included]
"""
def should_use_library(lib):
    def rule_says_yes(rule):
        useLib = None

        if rule["action"] == "allow":
            useLib = False
        elif rule["action"] == "disallow":
            useLib = True

        if "os" in rule:
            for key, value in rule["os"].items():
                os = platform.system()
                if key == "name":
                    if value == "windows" and os != 'Windows':
                        return useLib
                    elif value == "osx" and os != 'Darwin':
                        return useLib
                    elif value == "linux" and os != 'Linux':
                        return useLib
                elif key == "arch":
                    if value == "x86" and platform.architecture()[0] != "32bit":
                        return useLib

        return not useLib

    if not "rules" in lib:
        return True

    shouldUseLibrary = False
    for i in lib["rules"]:
        if rule_says_yes(i):
            return True

    return shouldUseLibrary

"""
[Get string of all libraries to add to java classpath]
"""
def get_classpath(lib, mcDir):
    cp = []

    for i in lib["libraries"]:
        if not should_use_library(i):
            continue

        libDomain, libName, libVersion = i["name"].split(":")
        jarPath = os.path.join(mcDir, "libraries", *
                               libDomain.split('.'), libName, libVersion)

        native = get_natives_string(i)
        jarFile = libName + "-" + libVersion + ".jar"
        if native != "":
            jarFile = libName + "-" + libVersion + "-" + native + ".jar"

        cp.append(os.path.join(jarPath, jarFile))

    cp.append(os.path.join(mcDir, "versions", lib["id"], f'{lib["id"]}.jar'))

    return os.pathsep.join(cp)

version = '1.16.5'
username = '{username}'
uuid = '{uuid}'
accessToken = '{token}'

mcDir = os.path.join(os.getenv('HOME'), '.minecraft')
nativesDir = os.path.join(os.getenv('HOME'), 'versions', version, 'natives')
clientJson = json.loads(
    Path(os.path.join(mcDir, 'versions', version, f'{version}.json')).read_text())
classPath = get_classpath(clientJson, mcDir)
mainClass = clientJson['mainClass']
versionType = clientJson['type']
assetIndex = clientJson['assetIndex']['id']

debug(classPath)
debug(mainClass)
debug(versionType)
debug(assetIndex)

subprocess.call([
    '/usr/bin/java',
    f'-Djava.library.path={nativesDir}',
    '-Dminecraft.launcher.brand=custom-launcher',
    '-Dminecraft.launcher.version=2.1',
    '-cp',
    classPath,
    'net.minecraft.client.main.Main',
    '--username',
    username,
    '--version',
    version,
    '--gameDir',
    mcDir,
    '--assetsDir',
    os.path.join(mcDir, 'assets'),
    '--assetIndex',
    assetIndex,
    '--uuid',
    uuid,
    '--accessToken',
    accessToken,
    '--userType',
    'mojang',
    '--versionType',
    'release'
])

To run Minecraft with Forge (change C:\Users\nov11\AppData\Roaming/.minecraft/to your MineCraft path :) [Just for people who are a bit too lazy to search on Google...] Special thanks to ammarx for his TagAPI_3 (Github) which was used to create this command. Arguments are separated line by line to make it easier to find useful ones.

java
-Xms1024M
-Xmx1024M
-XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump
-Djava.library.path=C:\Users\nov11\AppData\Roaming/.minecraft/versions/1.12.2/natives
-cp
C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/minecraftforge/forge/1.12.2-14.23.5.2775/forge-1.12.2-14.23.5.2775.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/minecraft/launchwrapper/1.12/launchwrapper-1.12.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/ow2/asm/asm-all/5.2/asm-all-5.2.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/jline/jline/3.5.1/jline-3.5.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/java/dev/jna/jna/4.4.0/jna-4.4.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/typesafe/akka/akka-actor_2.11/2.3.3/akka-actor_2.11-2.3.3.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/typesafe/config/1.2.1/config-1.2.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/scala-lang/scala-actors-migration_2.11/1.1.0/scala-actors-migration_2.11-1.1.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/scala-lang/scala-compiler/2.11.1/scala-compiler-2.11.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/scala-lang/plugins/scala-continuations-library_2.11/1.0.2/scala-continuations-library_2.11-1.0.2.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/scala-lang/plugins/scala-continuations-plugin_2.11.1/1.0.2/scala-continuations-plugin_2.11.1-1.0.2.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/scala-lang/scala-library/2.11.1/scala-library-2.11.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/scala-lang/scala-parser-combinators_2.11/1.0.1/scala-parser-combinators_2.11-1.0.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/scala-lang/scala-reflect/2.11.1/scala-reflect-2.11.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/scala-lang/scala-swing_2.11/1.0.1/scala-swing_2.11-1.0.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/scala-lang/scala-xml_2.11/1.0.2/scala-xml_2.11-1.0.2.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/lzma/lzma/0.0.1/lzma-0.0.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/sf/jopt-simple/jopt-simple/5.0.3/jopt-simple-5.0.3.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/java3d/vecmath/1.5.2/vecmath-1.5.2.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/sf/trove4j/trove4j/3.0.3/trove4j-3.0.3.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/apache/maven/maven-artifact/3.5.3/maven-artifact-3.5.3.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/mojang/patchy/1.1/patchy-1.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/oshi-project/oshi-core/1.1/oshi-core-1.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/java/dev/jna/jna/4.4.0/jna-4.4.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/java/dev/jna/platform/3.4.0/platform-3.4.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/ibm/icu/icu4j-core-mojang/51.2/icu4j-core-mojang-51.2.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/sf/jopt-simple/jopt-simple/5.0.3/jopt-simple-5.0.3.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/paulscode/codecjorbis/20101023/codecjorbis-20101023.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/paulscode/codecwav/20101023/codecwav-20101023.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/paulscode/libraryjavasound/20101123/libraryjavasound-20101123.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/paulscode/librarylwjglopenal/20100824/librarylwjglopenal-20100824.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/paulscode/soundsystem/20120107/soundsystem-20120107.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/io/netty/netty-all/4.1.9.Final/netty-all-4.1.9.Final.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/google/guava/guava/21.0/guava-21.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/apache/commons/commons-lang3/3.5/commons-lang3-3.5.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/commons-io/commons-io/2.5/commons-io-2.5.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/commons-codec/commons-codec/1.10/commons-codec-1.10.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/java/jinput/jinput/2.0.5/jinput-2.0.5.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/net/java/jutils/jutils/1.0.0/jutils-1.0.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/google/code/gson/gson/2.8.0/gson-2.8.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/mojang/authlib/1.5.25/authlib-1.5.25.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/mojang/realms/1.10.22/realms-1.10.22.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/apache/commons/commons-compress/1.8.1/commons-compress-1.8.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/apache/httpcomponents/httpclient/4.3.3/httpclient-4.3.3.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/commons-logging/commons-logging/1.1.3/commons-logging-1.1.3.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/apache/httpcomponents/httpcore/4.3.2/httpcore-4.3.2.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/it/unimi/dsi/fastutil/7.1.0/fastutil-7.1.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/apache/logging/log4j/log4j-api/2.8.1/log4j-api-2.8.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/apache/logging/log4j/log4j-core/2.8.1/log4j-core-2.8.1.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/lwjgl/lwjgl/lwjgl/2.9.4-nightly-20150209/lwjgl-2.9.4-nightly-20150209.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/lwjgl/lwjgl/lwjgl_util/2.9.4-nightly-20150209/lwjgl_util-2.9.4-nightly-20150209.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/lwjgl/lwjgl/lwjgl-platform/2.9.4-nightly-20150209/lwjgl-platform-2.9.4-nightly-20150209.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/lwjgl/lwjgl/lwjgl/2.9.2-nightly-20140822/lwjgl-2.9.2-nightly-20140822.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/org/lwjgl/lwjgl/lwjgl_util/2.9.2-nightly-20140822/lwjgl_util-2.9.2-nightly-20140822.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/mojang/text2speech/1.10.3/text2speech-1.10.3.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/com/mojang/text2speech/1.10.3/text2speech-1.10.3.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/ca/weblite/java-objc-bridge/1.0.0/java-objc-bridge-1.0.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/libraries/ca/weblite/java-objc-bridge/1.0.0/java-objc-bridge-1.0.0.jar;C:\Users\nov11\AppData\Roaming/.minecraft/versions/1.12.2/1.12.2.jar
net.minecraft.launchwrapper.Launch
--width
854
--height
480
--username
Ishikawa
--version
1.12.2-forge1.12.2-14.23.5.2775
--gameDir
C:\Users\nov11\AppData\Roaming/.minecraft
--assetsDir
C:\Users\nov11\AppData\Roaming/.minecraft/assets
--assetIndex
1.12
--uuid
N/A
--accessToken
aeef7bc935f9420eb6314dea7ad7e1e5
--userType
mojang
--tweakClass
net.minecraftforge.fml.common.launcher.FMLTweaker
--versionType
Forge

Just when other solutions don't work. accessToken and uuid can be acquired from Mojang Servers, check other anwsers for details.

Edit (26.11.2018): I've also created Launcher Framework in C# (.NET Framework 3.5), which you can also check to see how launcher should work Available Here

Just create this batch command file in your game directory. Bat file takes one argument %1 as the username.

Also, I use a splash screen to make pretty. You will NOT be able to play online, but who cares.

Adjust your memory usage to fit your machine (-Xmx & -Xmns).

NOTE: this is for version of minecraft as of 2016-06-27

@ECHO OFF
SET DIR=%cd%
SET JAVA_HOME=%DIR%\runtime\jre-x64\1.8.0_25
SET JAVA=%JAVA_HOME%\bin\java.exe
SET LOW_MEM=768M
SET MAX_MEM=2G
SET LIBRARIES=versions\1.10.2\1.10.2-natives-59894925878961
SET MAIN_CLASS=net.minecraft.client.main.Main
SET CLASSPATH=libraries\com\mojang\netty\1.6\netty-1.6.jar;libraries\oshi-project\oshi-core\1.1\oshi-core-1.1.jar;libraries\net\java\dev\jna\jna\3.4.0\jna-3.4.0.jar;libraries\net\java\dev\jna\platform\3.4.0\platform-3.4.0.jar;libraries\com\ibm\icu\icu4j-core-mojang\51.2\icu4j-core-mojang-51.2.jar;libraries\net\sf\jopt-simple\jopt-simple\4.6\jopt-simple-4.6.jar;libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar;libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar;libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar;libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar;libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar;libraries\io\netty\netty-all\4.0.23.Final\netty-all-4.0.23.Final.jar;libraries\com\google\guava\guava\17.0\guava-17.0.jar;libraries\org\apache\commons\commons-lang3\3.3.2\commons-lang3-3.3.2.jar;libraries\commons-io\commons-io\2.4\commons-io-2.4.jar;libraries\commons-codec\commons-codec\1.9\commons-codec-1.9.jar;libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar;libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar;libraries\com\google\code\gson\gson\2.2.4\gson-2.2.4.jar;libraries\com\mojang\authlib\1.5.22\authlib-1.5.22.jar;libraries\com\mojang\realms\1.9.3\realms-1.9.3.jar;libraries\org\apache\commons\commons-compress\1.8.1\commons-compress-1.8.1.jar;libraries\org\apache\httpcomponents\httpclient\4.3.3\httpclient-4.3.3.jar;libraries\commons-logging\commons-logging\1.1.3\commons-logging-1.1.3.jar;libraries\org\apache\httpcomponents\httpcore\4.3.2\httpcore-4.3.2.jar;libraries\it\unimi\dsi\fastutil\7.0.12_mojang\fastutil-7.0.12_mojang.jar;libraries\org\apache\logging\log4j\log4j-api\2.0-beta9\log4j-api-2.0-beta9.jar;libraries\org\apache\logging\log4j\log4j-core\2.0-beta9\log4j-core-2.0-beta9.jar;libraries\org\lwjgl\lwjgl\lwjgl\2.9.4-nightly-20150209\lwjgl-2.9.4-nightly-20150209.jar;libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.4-nightly-20150209\lwjgl_util-2.9.4-nightly-20150209.jar;versions\1.10.2\1.10.2.jar
SET JAVA_OPTIONS=-server -splash:splash.png -d64 -da -dsa -Xrs -Xms%LOW_MEM% -Xmx%MAX_MEM% -XX:NewSize=%LOW_MEM% -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -XX:+DisableExplicitGC -Djava.library.path=%LIBRARIES% -cp %CLASSPATH%  %MAIN_CLASS%

start /D %DIR% /I /HIGH %JAVA% %JAVA_OPTIONS% --username %1 --version 1.10.2 --gameDir %DIR% --assetsDir assets --assetIndex 1.10 --uuid 2536abce90e8476a871679918164abc5 --accessToken 99abe417230342cb8e9e2168ab46297a --userType legacy --versionType release --nativeLauncherVersion 307

Those are all ways to start the standard minecraft launcher with those credentials in the text boxes.

There used to be a way to login to minecraft without the launcher using the command line, but it has since been patched.

If you want to make a custom launcher using the command line then good luck, the only way to login to the minecraft jar(IE: the way the launcher does it) is to send a post request to https://login.minecraft.net/ with the username,password,launcher version, and a RSA key. It then parses the pseudo Json, and uses the session token from that to authenticate the jar from the command line with a load of arguments.

If you are trying to make a minecraft launcher and you have no knowledge of java,http requests or json then you have no chance.

Swift