Linuxers explains the differences between su and su -
When you use Debian/Ubuntu for a long time, you tend to forget about su and gradually you both grow apart. I witnessed the same thing yesterday. I was working in a lab and my friend asked me, Why you use su -. Why not a simple su -. I replied, "Duh!" and then sat silently the rest of the time wondering why I couldn't remember a thing about the command which has been hard-coded in my brain all this time while my friend enjoyed the blackout.Differences between su and su -
