Migrate you URL nicknames from Opera to Firefox

Follow those instructions:
 - under Opera, export your bookmarks (e.g. to /tmp/bookmarks.adr file)
 - into a console, parse the file like that :
cat /tmp/bookmarks.adr |tr -d '\n' |sed -e 's/#/\n/g;' |grep "SHORT NAME" |sed -e 's/.*URL=\([^ \t]*\)[ \t].*SHORT[ ]NAME=\([^ \t]*\)[ \t].*$/\2\t\1/g;' > /tmp/urlAlias.txt
 - under Firefox, go to Preferences of Url Alias add-on
 - copy/paste contents of /tmp/urlAlias.txt in "Configuration" panel