Error fetching the value from a shell script executed by root, when doing "su - oracle"

Problem:
Inside a new bash shell session, executed as user "oracle", like this:

su - oracle <<!

instructions here

!

I was not able to save the value of a string extracted from an xml file in a session variable.
I tried all possible variants (I thought), but was still unable to get my shell script to hold the value in a variable and use it locally within the oracle user session.

Solution:
Use backslash around the entire command, marked in yellow below:

su - oracle <<!
export CNTXT_FILE_PERL_VERSION=\`grep PERL5LIB \$CONTEXT_FILE | awk -F "site_perl/" '{print \$2}' | cut -f 1 -d":"\`
!

Credit goes to an experienced and clever colleague of mine, who shall remain nameless unless he actively wants his name listed on my blog ;-)