duncan@duncan-laptop:~$ which firefox /usr/bin/firefox
duncan@duncan-laptop:/usr/bin$ ls -l firefox lrwxrwxrwx 1 root root 11 2009-11-05 22:02 firefox -> firefox-3.5
duncan@ duncan- laptop: ~$ which firefox
/usr/bin/firefox
duncan@ duncan- laptop: /usr/bin$ ls -l firefox
lrwxrwxrwx 1 root root 11 2009-11-05 22:02 firefox -> firefox-3.5