I agree that it might be better. You can always do things better - however the price is often too much to optimize. But it is far better than most of the code that I have seen (like megabytes of ksh code that used global variables shared between thousands of files creating/closing a new connection to oracle every 10 seconds). In fact in my company there is a tool that fails whenever you enter non alphanumeric character in it - and the tool is used in hundreds of divisions (one can even implant own commands to execute with ROOT privileges.... standard code created by "professionals"). I guess that this code is far better than such examples - thus it does not seen like a result of "beginner's work".

Code:

LD_LIBRARY_PATH_64=${ORACLE_HOME}/lib

I see that this line should be quoted. Couple of others as well.
Would work with modern shells but would fail with many others.

Correct.

You should always try alternative solutions if you cannot find the bug and the alternative solution is simple/quick to implement. After your alternative code works you might trace the source by comparing the two versions.

I haven't worked in ksh for over a year. However I tend to use $() instead of ``. Sorry for inconvenience if the $(read LINE) would not return LINE to the parent.
In that case the line written by me should be: