Wizard to install the current version of JDownloader (jdownloader.org) on raspberry pi (running osmc or another linux). You can install (together or individually) latest java for RPI, download and install headless JDownloader (my.jdownloader.org) and create service to start JDownloader after boot and restart automatically after crash.

osmc-java-jdownloader-installer.sh

#!/bin/bash

# Script: osmc-java-jdownloader-installer.sh
# Author: Jozef Pažin
# Description: Wizard to install the current version of java and/or jdownloader on raspberry pi running osmc.
# License: MIT | use arbitrarily, attribution is not required
# How to run:
# - Check if this code is correct first because this script need to be run under root and run gist
#   from web is not recommended in terms of security only that you know exactly what it does. Check it:
#   curl -Ls https://gist.github.com/atiris/34dc670264274b3a472f2a718e4de83a/raw | nano -
# - And then run it with command (this way support 'read' user inputs):
#
#   SCRIPT=`curl -Ls https://gist.github.com/atiris/34dc670264274b3a472f2a718e4de83a/raw`; sudo bash -c "$SCRIPT"
#
# Inspiration:
# - https://gist.github.com/ribasco/fff7d30b31807eb02b32bcf35164f11f
# - https://github.com/PlusMinus0/headless-jd2-docker
# - https://gist.github.com/leosuncin/50367b3c905fe8699b13bd85ad26071b

if [[ "$EUID" -ne 0 ]]; then
  echo ""
  echo "Please login as root: sudo su"
  echo ""
  return
fi

RUN_AS_USER=root

# Colors
NC='\033[0m'
RED='\033[0;91m'
GREEN='\033[0;92m'
BLUE='\033[0;94m'
YELLOW='\033[0;93m'

echo ""
# Java

JAVA_VERSION_LOCAL=`echo $(java -version 2>&1)| awk -F \" '{print $2}'`
if [[ $JAVA_VERSION_LOCAL = *[!\ ]* ]]; then
  echo -e "Local java version is ""$RED""$JAVA_VERSION_LOCAL""$NC"
  response=n
  echo ""
  echo -e "$RED""Install java anyway?""$NC"
  read -p "[y/N] " response
  response=${response,,}
else
  echo -e "$YELLOW""Java is not installed.""$GREEN"" I will run the installation for you.""$NC"
  response=y
fi

if [[ $response =~ ^(yes|y) ]]; then
  # original java first
  echo "-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: SKS 1.1.5
Comment: Hostname: keyserver.ubuntu.com
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=CziK
-----END PGP PUBLIC KEY BLOCK-----" > temporarykey.txt

  apt-key add temporarykey.txt

  rm -f temporarykey.txt

  echo debconf shared/accepted-oracle-license-v1-1 select true | sudo debconf-set-selections
  echo debconf shared/accepted-oracle-license-v1-1 seen true | sudo debconf-set-selections
  echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu xenial main" | tee /etc/apt/sources.list.d/webupd8team-java.list
  echo "deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu xenial main" | tee -a /etc/apt/sources.list.d/webupd8team-java.list
  echo -e "$NC""Remove source with: rm /etc/apt/sources.list.d/webupd8team-java.list"
  
  apt update
  apt install -f
  dpkg --configure -a
  apt install -y oracle-java8-installer

  apt install -y oracle-java8-set-default

  echo ""
  echo -e "$GREEN""Java installation script is complete... Testing.""$NC"
  JAVA_VERSION_LOCAL=`echo $(java -version 2>&1)| awk -F \" '{print $2}'`
  if [[ $JAVA_VERSION_LOCAL = *[!\ ]* ]]; then
    echo "Actual java vesion on your system is:"
    java -version
  else
    # alternative java installer
    echo -e "$RED""First attempt failed! I am trying to install the openjdk version...""$NC"
    apt install -y openjdk-8-jdk
    
    echo -e "$GREEN""Java installation script is complete, again... Testing.""$NC"
  fi
else
  echo "Java installation skipped."
fi

JAVA_VERSION_LOCAL=`echo $(java -version 2>&1)| awk -F \" '{print $2}'`
if [[ $JAVA_VERSION_LOCAL = *[!\ ]* ]]; then
  echo "Actual java vesion on your system is:"
  java -version
else
  echo -e "$RED""Java is still not installed!""$NC"
  echo "There is probably a new version of java and the installer wasn't yet updated to reference it."
  echo -e "$GREEN""You can do this steps to install java manually:""$NC"
  echo ""
  echo "Check if your system supports openjdk alternative and use it."
  echo ""
  echo "Or harder way:"
  echo "Open oracle download site https://www.oracle.com/technetwork/java/javase/downloads/index.html"
  echo "Find Java SE 8 link, accept license and select jdk-8uXXX-linux-arm32-vfp-hflt.tar.gz version"
  echo "Download it (version 8 is not supported, so you need to have an oracle account)"
  echo "to any directory and unpack with command:"
  echo -e "$BLUE""tar -xzf jdk-8uXXX-linux-arm32-vfp-hflt.tar.gz""$NC"
  echo "Create /usr/local/java directory mkdir -p -v /usr/local/java"
  echo "Move unpacked to /usr/local/java/jdk1.8.0_XXX:"
  echo -e "$BLUE""mv /path/to/jdk1.8.0_XXX /usr/local/java/jdk1.8.0_XXX""$NC"
  echo "Update java alternatives with new path:"
  echo -e "$BLUE""sudo update-alternatives --install \"/usr/bin/java\" \"java\" \"/usr/local/java/jdk1.8.0_XXX/bin/java\" 1""$NC"
  echo "Set default java with:"
  echo -e "$BLUE""sudo update-alternatives --set java /usr/local/java/jdk1.8.0_XXX/bin/java""$NC"
  
  response=n
  echo ""
  echo -e "$RED""Continue anyway?""$NC"
  read -p "[y/N] " response
  response=${response,,}
  
  if [[ $response =~ ^(no|n) ]]; then
    exit 0
  fi
fi

echo ""
# JDownloader

if [ -e /opt/JDownloader/JDownloader.jar ]; then
  FILE_DATE=$(date -r /opt/JDownloader/JDownloader.jar +%Y-%m-%d)
  echo -e "JDownloader already installed. File date is ""$RED""$FILE_DATE""$NC""."
  echo ""
  response=n
  echo -e "$RED""Remove it and install actual JDownloader anyway?""$NC"
  read -p "[y/N] " response
  response=${response,,} 
else
  echo -e "$YELLOW""JDownloader is not installed.""$GREEN"" Let me run it.""$NC"
  response=y
fi

if [[ $response =~ ^(yes|y) ]]; then
  echo -e "$BLUE"
  echo "I'll download JDownloader from official site jdownloader.org."
  echo "Then I will run the installation process several times, until JDownloader"
  echo "ask you for login and password. Please press \"y\" at that time, and set"
  echo "your credentials from my.jdownloader.org (you must first be registered)."
  echo "Then wait some time (few seconds) until JDownloader save this settings"
  echo "and interrupt JDownloader installation by pressing \"CTRL+C\"."
  echo "You can continue in next step with installation of daemon,"
  echo "to start JDownloader automatically on reboot or after crash."
  echo -e "$NC"
  echo "Press enter to continue"
  read
  echo -e "$GREEN""OK""$NC"
  echo ""

  if [[ "$RUN_AS_USER" == 'root' ]] && [[ `id -u osmc 2>/dev/null || echo -1` -ge 0 ]]; then 
    echo "Install JDownloader with 'osmc' user rights."
    RUN_AS_USER=osmc
  fi
  if [[ "$RUN_AS_USER" == 'root' ]] && [[ `id -u pi 2>/dev/null || echo -1` -ge 0 ]]; then 
    echo "Install JDownloader with 'pi' user rights."
    RUN_AS_USER=pi
  fi
  if [ "$RUN_AS_USER" == 'root' ]; then 
    echo "Installing as 'root'?"
    echo "Running JDownloader under 'root' user is not recommended."
    response=xxxundefinedxxx
    echo ""
    echo -e "$RED""Can you type another user name?""$NC"
    read -p "Username " response
    response=${response,,}
    if [[ $response =~ ^(xxxundefinedxxx) ]]; then
      echo "Well, ok then, I'll use 'root' for JDownloader."
    else
      echo "JDownloader will be run with $response rights."
      RUN_AS_USER=$response
    fi
  fi

  if [ ! -d /opt/JDownloader ]; then
    mkdir -p /opt/JDownloader
    echo "Folder /opt/JDownloader created."
  else
    rm -rf /opt/JDownloader/*
    echo "Folder for JDownloader cleaned."
  fi
  chown -fR $RUN_AS_USER:users /opt/JDownloader

  sudo -u $RUN_AS_USER wget -O /opt/JDownloader/JDownloader.jar --progress=bar:force http://installer.jdownloader.org/JDownloader.jar

  echo -e "$BLUE""Starting JDownloader installation."
  echo "Wait for the login / password request."
  echo "Register here: https://my.jdownloader.org/"
  echo -e "$NC"

  doNextLoop=1
  while [ $doNextLoop -eq 1 ]
  do
    doNextLoop=0
    sudo -u $RUN_AS_USER java -jar /opt/JDownloader/JDownloader.jar -norestart
    echo -e "$RED""You have already seen a request to enter your login information?""$NC"
    read -p "[y/N] " response
      response=${response,,}
      if [[ $response =~ ^(no|n| ) ]] || [[ -z $response ]]; then
        doNextLoop=1
      fi
  done
  echo -e "$GREEN""JDownloader instalation is complete.""$NC"
  
  echo ""
  echo -e "$GREEN""Note about download youtube videos""$NC"
  echo ""
  echo "To download youtube videos you need to install ffmpeg"
  echo "You can build it yourself or use static build. For static build:"
  echo "Download armhf version from johnvansickle.com/ffmpeg"
  echo -e "$BLUE""wget https://johnvansickle.com/ffmpeg/releases/ffmpeg-release-armhf-static.tar.xz""$NC"
  echo "Extract it anywhere"
  echo -e "$BLUE""tar -xvf ffmpeg-release-armhf-static.tar.xz""$NC"
  echo "And set 2 paths to ffmpeg binaries in advanced settings of selected jDownloader"
  echo "You can use my.jdownloader for this, go to settings, advanced and search for 'ffmpeg path'"
else
  echo "JDownloader installation skipped."
fi

echo ""
# Service systemd jdownloader

if [ -e /etc/systemd/system/jdownloader.service ]; then
  FILE_DATE=$(date -r /etc/systemd/system/jdownloader.service +%Y-%m-%d)
  echo -e "Service jdownloader already exists. File date is ""$RED""$FILE_DATE""$NC""."
  echo ""
  response=n
  echo -e "$RED""Replace existing with default service implementation?""$NC"
  read -p "[y/N] " response
  response=${response,,}
else
  echo -e "$YELLOW""Service for jdownloader not exists yet.""$GREEN"" No worries, I will create it.""$NC"
  response=y
fi

if [[ $response =~ ^(yes|y) ]]; then
  echo ""
  touch /opt/JDownloader/JDownloader.pid

  if [[ "$RUN_AS_USER" == 'root' ]] && [[ `id -u osmc 2>/dev/null || echo -1` -ge 0 ]]; then 
    echo "Using 'osmc' user rights."
    RUN_AS_USER=osmc
  fi
  if [[ "$RUN_AS_USER" == 'root' ]] && [[ `id -u pi 2>/dev/null || echo -1` -ge 0 ]]; then 
    echo "Using 'pi' user rights."
    RUN_AS_USER=pi
  fi
  if [ "$RUN_AS_USER" == 'root' ]; then 
    echo "You want to start the service as 'root' user?"
    echo "Running JDownloader under 'root' user is not recommended."
    response=xxxundefinedxxx
    echo ""
    echo -e "$RED""Can you type another user name?""$NC"
    read -p "Username " response
    response=${response,,}
    if [[ $response =~ ^(xxxundefinedxxx) ]]; then
      echo "Well, ok then, I'll use 'root' for JDownloader service."
    else
      echo "JDownloader will be run with $response rights."
      RUN_AS_USER=$response
    fi
  fi
  echo "[Unit]
Description=JDownloader2 headless service
After=network.target

[Service]
# User=""$RUN_AS_USER"" # not all jDownloader services working with non root user
Type=simple
Environment=JD_HOME=/opt/JDownloader
WorkingDirectory=/opt/JDownloader
ExecStart=/usr/bin/java -Djava.awt.headless=true -jar /opt/JDownloader/JDownloader.jar
RemainAfterExit=yes
Restart=on-failure
RestartSec=10s

[Install]
WantedBy=multi-user.target
" > /etc/systemd/system/jdownloader.service

  if [ -e /etc/systemd/system/jdownloader.service ]; then
    systemctl daemon-reload
    echo -e "Service /etc/systemd/user/jdownloader.service > ""$GREEN""created OK""$NC"
    systemctl enable jdownloader
    echo -e "Service jdownloader enabled > ""$GREEN""OK""$NC"
    systemctl start jdownloader

    SERVICE_STATE=$(ps -ef | grep -v grep | grep JDownloader | wc -l)
    if [ "$SERVICE_STATE" -eq 0 ]; then
      echo -e "$RED""WARNING! Service jdownloader is down.""$NC"
    else
      echo -e "Service jdownloader started > ""$GREEN""OK""$NC"
    fi

    echo ""
    echo -e "$GREEN""Service installation is complete.""$NC"
    echo "You can check service status with: systemctl status jdownloader"
    echo "Sometimes jDownloader create file or directory with root owner rights"
    echo "To fix it you can crate cron job:"
    echo "sudo crontab -u root -e"
    echo "And run chow for your user (osmc) on your requested directory like this:"
    echo "*/5 * * * * sudo chown -R osmc:osmc /home/osmc/Download >/dev/null 2>&1"
  else
    echo -e "$RED""ERROR! I can not create a service.""$NC"
  fi
else
  echo "Service installation skipped."
fi

echo ""
# Final message

echo -e "$GREEN""That's all, I hope everything works for you.""$NC"
echo -e "$GREEN""Now you can check JDownloader on https://my.jdownloader.org/""$NC"

great script worked like a charm!!!
Thanks for the contribution!