How to find Default Web Browser in Linux ?

[ahenry3068]

I want a program I'm working on to open a web page using the default browser.    Program is cross-platform and will be compiled for both WIN64 & LINUX.    Windows is easy here I just shell("start "+URL$).    I've figured out that in linux I can just shell "firefox  "+URL$ or shell "google-chrome " + URL$ and that works, but I don't know how to find the DEFAULT browser it's not in the ENVIRON$() and I'm not really sure how to go about it.