Launch Minecraft from command line - username and password as prefix

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

You can do this, you just need to circumvent the launcher.

In %appdata%\.minecraft\bin (or ~/.minecraft/bin on unixy systems), there is a minecraft.jar file. This is the actual game - the launcher runs this.

Invoke it like so:

java -Xms512m -Xmx1g -Djava.library.path=natives/ -cp "minecraft.jar;lwjgl.jar;lwjgl_util.jar" net.minecraft.client.Minecraft <username> <sessionID>

Set the working directory to .minecraft/bin.

To get the session ID, POST (request this page):

https://login.minecraft.net?user=<username>&password=<password>&version=13

You'll get a response like this:

1343825972000:deprecated:SirCmpwn:7ae9007b9909de05ea58e94199a33b30c310c69c:dba0c48e1c584963b9e93a038a66bb98

The fourth field is the session ID. More details here. Read those details, this answer is outdated

Here's an example of logging in to minecraft.net in C#.