This is all too confusing. All you have to do is put the text in a file called
.Xclients in your home directory that will specify the default desktop. To see what's installed on your system and find out what they are called do:
You will see files with an extension
.desktop, for example
To make mate your default desktop you can then edit
~/.Xclients in your home folder, if you have such a file, or create one with nothing in it except your chosen desktop type (without the .desktop extension) with a -session appended:
echo mate-session > ~/.Xclients
should do this just fine. You can then log off and log back in, or if you are connected using xrdp you can restart xrdp, which will log you off and then you can log back in, (just log off and log back in, its stupid to get confused by restarting xrdp etc...)
Forget switchdesk - its broken in Fedora 23.
Forget most of what's on the web for prior Fedora versions, Ubuntu etc... None of it works.