anchor.diff:  FROM x11vnc/baseimage:0.9.22
   LABEL maintainer Xiangmin Jiao <xmjiao@gmail.com>
   
  +ARG DOCKER_LANG=en_US
  +ARG DOCKER_TIMEZONE=America/New_York
  +
  +ENV LANG=$DOCKER_LANG.UTF-8 \
  +    LANGUAGE=$DOCKER_LANG:UTF-8 \
  +    LC_ALL=$DOCKER_LANG.UTF-8
  +
   WORKDIR /tmp
   
   ARG DEBIAN_FRONTEND=noninteractive
   
   # Install some required system tools and packages for X Windows
  -RUN apt-get update && \
  +RUN locale-gen $LANG && \
  +    dpkg-reconfigure -f noninteractive locales && \
  +    apt-get update && \
       apt-get install -y --no-install-recommends \
           man \
           sudo \
  
positive.code: # Customization for user and location
  ########################################################
  # Set up user so that we do not run as root
  ENV LANG=en_US.UTF-8 \
      LANGUAGE=en_US:en \
      LC_ALL=en_US.UTF-8
  
  ENV DOCKER_USER=ubuntu \
      DOCKER_SHELL=/usr/bin/zsh
  
  
negative.code:     DOCKER_HOME=/home/$DOCKER_USER \
      HOME=/home/$DOCKER_USER
  
  # Change the default timezone to $DOCKER_TIMEZONE
  # Disable forward logging (https://github.com/phusion/baseimage-docker/issues/186)
  # Run ldconfig so that /usr/local/lib etc. are in the default
  # search path for dynamic linker
  RUN useradd -m -s $DOCKER_SHELL -G sudo,docker_env $DOCKER_USER && \
      echo "$DOCKER_USER:docker" | chpasswd && \
      echo "$DOCKER_USER ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers && \
      echo "$DOCKER_TIMEZONE" > /etc/timezone && \
      ln -s -f /usr/share/zoneinfo/$DOCKER_TIMEZONE /etc/localtime && \
      touch /etc/service/syslog-forwarder/down && \
      ldconfig
  
  