Enviroment variable in .desktop

[Qihua Wang <qihua wang alcatel com>]

Hi,
Is there any way to put in text in the xxx.desktop for Exec=  line that would pick up, not the literal text, but a value from
elsewhere? Like an environment variable? I'd like to have the launch location specified in .desktop using environment variable 
since I don't know where the user
installs the application for launcher.

-Qihua