Using ksh set -u breaks xinit script...

[Dan Prener]

If all uses of undefined shell variables are to be considered errors,
then it becomes very difficult to get first-time switches and to
keep other state.  How, for example does shell script s1 tell whether
shell script s2 has been executed?  Isn't this usually done by testing
some shell variable that will have been set by s2, or left unset if
s2 has not been executed?
-- 
                                   Dan Prener (prener @ watson.ibm.com)