cat /var/lib/dpkg/alternatives/x-www-browser
auto
/usr/bin/x-www-browser
x-www-browser.1.gz
/usr/share/man/man1/x-www-browser.1.gz

/usr/bin/iceweasel
70
/usr/share/man/man1/iceweasel.1.gz
/usr/bin/opera-next
999
/usr/share/man/man1/opera-next.1.gz
/usr/bin/google-chrome
100
/usr/share/man/man/google-chrome.1