Common Desktop Environment - one of the oldest desktop environment for UNIX
  environment since 90's where most of old-school programmers had their good
  time with this graphical user interface. Today, this desktop environment had
  been revived so user with modern PCs can try to install this desktop
  environment and feel the classical throwback in the 90's.
  Today, I'm gonna write on how to install and set up the Common Desktop
  Environment (CDE) and this guide is heavily aimed at FreeBSD users (sorry,
  Linux users!)
  1. Installing CDE interface
  First of all, you will need to obtain the latest ports package first which you
  will need to compile it yourself.
  $ portsnap fetch
  $ portsnap extract 
  Then, go to CDE ports directory via the command below:
  $ /usr/ports/x11/cde
  Next, launch the command below to begin building process.
  $ make install  
  NOTE: If you're having an error during compilation process such as ksh93 is
  not found, you will need to make a new copy of ksh executable as ksh93 via the
  command below:
  $ cp /usr/local/bin/ksh /bin/ksh93 
  1. Configuring CDE interface
  Add these line below in /etc/rc.local to start CDE on boot:
/usr/local/dt/bin/dtlogin
dtspc stream tcp4   nowait  root    /usr/local/dt/bin/dtspcd /usr/local/dt/bin/dtspcd
cmsd/2-5    dgram rpc/udp4 wait root /usr/local/dt/bin/rpc.cmsd rpc.cmsd
rpcbind_enable="YES"
inetd_enable="YES"
127.0.0.1   HOSTNAME