According to Wikipedia, the Common Desktop Environment was released under the GPL and at one time was ported to Debian. But searching through Debian's software repository, I was unable to find CDE. Is there a simple way to install CDE on Debian 8?
Motif (the toolkit powering CDE) was (until recently) bogged down by licensing issues and therefore left in the dust by other toolkits like GTK and Qt. You can still
apt-get install mwm for the Motif Window Manager, but CDE is now even more obscure.
If you really want to install the Common Desktop Environment (where "common" means among what are now ancient commercial Unix systems), you need to first be comfortable with the fact that it is considered neither stable nor easy to use. The CDE LinuxBuild wiki says:
CDE on Linux is not yet to the point of being simple to package for distribution or a relatively simple to compile from the source archive.
(That said, CDE does list Debian and similar systems as supported platforms.)
That page has detailed directions for how to install and configure dependencies, clone the repository, "attempt to build" from source, test, and then (if you get this far) install. It also notes that the calendar and mail clients are known to not work.
This page is a bit dated; they do not acknowledge that Motif is now free (libre) software.
Sparky Linux contains a
cde-desktop package. Its repositories are the same as in debian, but additionally provides one repository with custom Sparky packages. The repo has three branches,
unstable, correspondending to current debian branches.
The package installs all CDE files in
/usr/dt and an xsession entry
CDE.desktop for display managers in
/usr/share/xsessions. Without a display manager you can start CDE with
I did a test install on debian stretch and so far it seems to run fine.