As a solaris newbie I was told by an experienced administrator don't assign any shell to root except for the bourne shell. I found out later the wisdom of this advice when a machine I was troubleshooting could not boot up into single user mode because the root account was assigned the korn shell and the korn shell was not available.
Because I prefer to work in the korn shell I found it troublesome to always have to load a second shell after I su'd to the root account. To get around the problem I added a few lines to the .profile account for root. The commands confirm that the korn shell is available and then replace the bourne shell with the korn shell. This same technique could be done with bash or cshell or any other shell.
By setting the ENV variable to /.kshrc I can add aliases and other customizations to roots shell environment, including them in the /.kshrc file.
# /.profile stty istrip stty erase "^H" ENV=/.kshrc;export ENV TERM=vt100;export TERM if [ -x /bin/ksh ] then exec /bin/ksh fi