MacOS X remove all Java installations

To remove all installed Java versions on MacOS X, run following commands in terminal:

Java Runtime Environment and Plugins

sudo rm -fr /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin
sudo rm -fr /Library/PreferencePanes/JavaControlPanel.prefPane
sudo rm -fr ~/Library/Application\ Support/Java
Java Development Kit

sudo rm -rf /Library/Java/JavaVirtualMachines/jdk<version>.jdk
Java Plugins

sudo rm -rf /Library/PreferencePanes/JavaControlPanel.prefPane
sudo rm -rf /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin
sudo rm -rf /Library/LaunchAgents/com.oracle.java.Java-Updater.plist
sudo rm -rf /Library/PrivilegedHelperTools/com.oracle.java.JavaUpdateHelper
sudo rm -rf /Library/LaunchDaemons/com.oracle.java.Helper-Tool.plist
sudo rm -rf /Library/Preferences/com.oracle.java.Helper-Tool.plist


Docker - stop & delete all containers and images

The following command deletes all Docker container and images:
#Stop all Docker containers
docker stop $(docker ps -a -q)

#Delete every Docker container
#Must be run as images are attached to containers
docker rm -f $(docker ps -a -q)

#Delete every Docker image
docker rmi -f $(docker images -q)


How to install Virtual Box Guest Additions in Debian VM

To install the VirtualBox Guest Additions into a Debian VM, follow these steps:

• Open a terminal and switch to root
su
• Update apt repository and install updates
apt-get update && apt-get upgrade
• Install packages for building kernel modules
apt-get install build-essential module-assistant
• Configure system for building kernel modules 
m-a prepare
• Mount VBoxAdditions ISO (if not mounted automatically)
mount /media/cdrom
• Run the installer script
sh /media/cdrom/VBoxLinuxAdditions.run
• Reboot VM to enable Guest Additions
reboot