Dockerfile for VNC Server running XFCE Desktop on Debian Jessie, version 2

Dockerfile

FROM debian:jessie

RUN apt-get update && apt-get install --no-install-recommends -y keyboard-configuration \
    && rm -rf /var/lib/apt/lists/*

RUN apt-get update && apt-get install --no-install-recommends -y gnome-icon-theme tightvncserver xorg xserver-xorg \
    xserver-xorg-video-dummy \
    && rm -rf /var/lib/apt/lists/*

RUN apt-get update && apt-get install --no-install-recommends -y xfce4 xfce4-goodies iceweasel \
    && rm -rf /var/lib/apt/lists/*

RUN groupadd  vuser && useradd -m -g vuser vuser

USER vuser

RUN mkdir ~/.vnc && echo thepassword | vncpasswd -f > ~/.vnc/passwd

RUN chmod 0600 ~/.vnc/passwd

#ENV USER vuser
WORKDIR /home/vuser

CMD USER=vuser && export USER && rm -rf /tmp && vncserver :3 && DISPLAY=localhost:3 && export DISPLAY && xterm

i ran in permission error can't remove /tmp permission denied