karthick@Ubuntu-desktop:~$ sudo update-alternatives --config x-www-browser
There are 3 choices for the alternative x-www-browser (providing /usr/bin/x-www-browser).

  Selection    Path                    Priority   Status
------------------------------------------------------------
  0            /usr/bin/google-chrome   200       auto mode
* 1            /usr/bin/firefox         40        manual mode
  2            /usr/bin/google-chrome   200       manual mode
  3            /usr/bin/opera           90        manual mode

xdg-settings set default-web-browser chromium-browser.desktop

export BROWSER=/usr/bin/firefox

sudo update-alternatives --config x-www-browser

sudo update-alternatives --config x-www-browser
sudo update-alternatives --config www-browser

/usr/bin/google-chrome -> /etc/alternatives/google-chrome -> /usr/bin/google-chrome-beta

sudo update-alternatives --install /usr/bin/x-www-browser x-www-browser /opt/yourapp/yourapp 200
sudo update-alternatives --set x-www-browser /opt/yourapp/yourapp