Legacy Launcher https://llaun.ch/ starter

tl_starter.sh

XMS="2048M"
XMX="2048M"
POSITIONAL=()
USERNAME=""
TL_MINECRAFT=${HOME}"/Minecraft"

while [[ $# -gt 0 ]]; do
  key="$1"

  case $key in
  -xmx | --xmx)
    XMX="$2"
    shift
    shift
    ;;
  -xms | --xms)
    XMS="$2"
    shift
    shift
    ;;
  -u | --username)
    USERNAME="$2"
    shift
    shift
    ;;
  -mc | --tl-minecraft-folder)
    TL_MINECRAFT="$2"
    shift
    shift
    ;;
  *)
    POSITIONAL+=("$1")
    shift
    ;;
  esac
done

set -- "${POSITIONAL[@]}"

if [ -z "$USERNAME" ]; then
  echo "Username is not passed"
  exit 1
fi

"${HOME}"/.tlauncher/mojang_jre/jre-legacy/linux/jre-legacy/bin/java \
	-XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 \
	-XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M \
	-XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:+ParallelRefProcEnabled \
	-Xms"${XMS}" -Xmx"${XMX}" \
	-Dfile.encoding=UTF-8 -Dlog4j.configurationFile="${TL_MINECRAFT}"/assets/log_configs/patched-variant-2.7.xml \
	-Djava.library.path="${TL_MINECRAFT}"/versions/OptiFine\ 1.16.5/natives \
	-Dminecraft.launcher.brand=java-minecraft-launcher \
	-Dminecraft.launcher.version=1.6.84-j \
	-cp "${TL_MINECRAFT}"/libraries/com/turikhay/ca-fixer/1.0/ca-fixer-1.0.jar:"${TL_MINECRAFT}"/libraries/optifine/OptiFine/1.16.5_HD_U_G8/OptiFine-1.16.5_HD_U_G8.jar:"${TL_MINECRAFT}"/libraries/optifine/launchwrapper/2.2/launchwrapper-2.2.jar:"${TL_MINECRAFT}"/libraries/ru/tlauncher/patchy/1.0.0/patchy-1.0.0.jar:"${TL_MINECRAFT}"/libraries/oshi-project/oshi-core/1.1/oshi-core-1.1.jar:"${TL_MINECRAFT}"/libraries/net/java/dev/jna/jna/4.4.0/jna-4.4.0.jar:"${TL_MINECRAFT}"/libraries/net/java/dev/jna/platform/3.4.0/platform-3.4.0.jar:"${TL_MINECRAFT}"/libraries/com/ibm/icu/icu4j/66.1/icu4j-66.1.jar:"${TL_MINECRAFT}"/libraries/com/mojang/javabridge/1.0.22/javabridge-1.0.22.jar:"${TL_MINECRAFT}"/libraries/net/sf/jopt-simple/jopt-simple/5.0.3/jopt-simple-5.0.3.jar:"${TL_MINECRAFT}"/libraries/io/netty/netty-all/4.1.25.Final/netty-all-4.1.25.Final.jar:"${TL_MINECRAFT}"/libraries/com/google/guava/guava/21.0/guava-21.0.jar:"${TL_MINECRAFT}"/libraries/org/apache/commons/commons-lang3/3.5/commons-lang3-3.5.jar:"${TL_MINECRAFT}"/libraries/commons-io/commons-io/2.5/commons-io-2.5.jar:"${TL_MINECRAFT}"/libraries/commons-codec/commons-codec/1.10/commons-codec-1.10.jar:"${TL_MINECRAFT}"/libraries/net/java/jinput/jinput/2.0.5/jinput-2.0.5.jar:"${TL_MINECRAFT}"/libraries/net/java/jutils/jutils/1.0.0/jutils-1.0.0.jar:"${TL_MINECRAFT}"/libraries/com/mojang/brigadier/1.0.17/brigadier-1.0.17.jar:"${TL_MINECRAFT}"/libraries/com/mojang/datafixerupper/4.0.26/datafixerupper-4.0.26.jar:"${TL_MINECRAFT}"/libraries/com/google/code/gson/gson/2.8.0/gson-2.8.0.jar:"${TL_MINECRAFT}"/libraries/by/ely/authlib/3.11.49.2/authlib-3.11.49.2.jar:"${TL_MINECRAFT}"/libraries/org/apache/commons/commons-compress/1.8.1/commons-compress-1.8.1.jar:"${TL_MINECRAFT}"/libraries/org/apache/httpcomponents/httpclient/4.3.3/httpclient-4.3.3.jar:"${TL_MINECRAFT}"/libraries/commons-logging/commons-logging/1.1.3/commons-logging-1.1.3.jar:"${TL_MINECRAFT}"/libraries/org/apache/httpcomponents/httpcore/4.3.2/httpcore-4.3.2.jar:"${TL_MINECRAFT}"/libraries/it/unimi/dsi/fastutil/8.2.1/fastutil-8.2.1.jar:"${TL_MINECRAFT}"/libraries/org/apache/logging/log4j/log4j-api/2.8.1/log4j-api-2.8.1.jar:"${TL_MINECRAFT}"/libraries/org/apache/logging/log4j/log4j-core/2.8.1/log4j-core-2.8.1.jar:"${TL_MINECRAFT}"/libraries/org/lwjgl/lwjgl/3.2.2/lwjgl-3.2.2.jar:"${TL_MINECRAFT}"/libraries/org/lwjgl/lwjgl-jemalloc/3.2.2/lwjgl-jemalloc-3.2.2.jar:"${TL_MINECRAFT}"/libraries/org/lwjgl/lwjgl-openal/3.2.2/lwjgl-openal-3.2.2.jar:"${TL_MINECRAFT}"/libraries/org/lwjgl/lwjgl-opengl/3.2.2/lwjgl-opengl-3.2.2.jar:"${TL_MINECRAFT}"/libraries/org/lwjgl/lwjgl-glfw/3.2.2/lwjgl-glfw-3.2.2.jar:"${TL_MINECRAFT}"/libraries/org/lwjgl/lwjgl-stb/3.2.2/lwjgl-stb-3.2.2.jar:"${TL_MINECRAFT}"/libraries/org/lwjgl/lwjgl-tinyfd/3.2.2/lwjgl-tinyfd-3.2.2.jar:"${TL_MINECRAFT}"/libraries/com/mojang/text2speech/1.11.3/text2speech-1.11.3.jar:"${TL_MINECRAFT}"/versions/OptiFine\ 1.16.5/OptiFine\ 1.16.5.jar \
	-Xss2M net.minecraft.launchwrapper.Launch \
	--username "${USERNAME}" --version OptiFine\ 1.16.5 \
	--gameDir "${TL_MINECRAFT}" \
	--assetsDir "${TL_MINECRAFT}"/assets \
	--assetIndex 1.16 --uuid 2e9ded2c7581310b9f54befadc79dc24 \
	--accessToken [Minecraft is a lie] \
	--userType legacy --versionType modified \
	--width 925 --height 530 --tweakClass optifine.OptiFineTweaker &>/dev/null & disown