Shell Programming and Scripting

I'm writing a script that does many things, but it runs as a root. It does some backups etc, and then it su's over to oracle user to do some oracle stuff, this way I don't have to worry about Oracle env variables etc. Saves time, headache etc.
The thing is that, this script worked perfectly on Solaris, but it not in Linux (Redhat and Suse).
Here is a snippet:
#!/usr/bin/ksh
## doing some maintenance as root user
tar -cvf /usr/home/dir
...
## Now do some oracle stuff###
SH_LOG=/tmp/script123.log
echo "Enter user name for oracle:"
read $ORA_USER
su - $ORA_USER "sqlplus -S -L / AS SYSDBA <<\EOF >$SH_LOG
SET HEADING OFF;
SELECT GROUP#, BYTES, STATUS FROM V\$LOG;
SPOOL OFF
EXIT;
EOF"
## EOF

This above script works and changes over to oracle user in Solaris, runs my sql commands and gives me a log. When I run it in Linux, it craps out. My guess it that "su -" does not pass the variables in Linux, so it doesn't understand $ORA_USER and $SH_LOG.
I even tried "su - $ORA_USER -c -m" options, they all failed to give me the desired results. Any ideas?
Thanks in advance.

-Nitin

check what is the default shell and what is the profile file loaded... i guess profile and shell settings could be the problem.. they might be different in your unix and linux box

The default shell in Linux as always is bash. I didn't write the script in bash, coz some Unix systems still don't have it. Hence, I prefer to use korn, coz it is standard across Unix. I've to run this script in a fleet of systems, so I don't want to change the shell and profile settings, all I want is that it execute my commnads in korn temporarily. Is there a way to tell what shell I want to use in 'su'.

Thanks for the reply,

Nitin

Even in unix "su - " do not pass env variables to the new shell... it is just "su"

Code:

     To become user bin while retaining your previously  exported
     environment, execute:

     example% su bin

    To become user bin but change the environment to what  would
     be expected if bin had originally logged in, execute:

     example% su - bin

You might be using ksh in your script, but check the default shell and profile that gets loaded when you do "su" or login for oracle user...

In unix it might be loading the correct profile what you wanted but in linux it might be loading some bash profile which don't have correct settings.. compare both profile files in unix and linux