The default shell for each user is stored in the /etc/passwd file on the end of each line. Change into single user mode (init S) then edit the passwd file using vi (vi /etc/passwd and change it.
That's the safe, recommended way to do it. If you like to live dangerously, you can simply make sure you're the only person logged in and do this in a terminal window: su (enter root password) gedit /etc/passwd & Then edit the passwd file in the Gnome text editor (gedit). Cheers Andrew. This message posted from opensolaris.org
