OK.. you really
should look at perlre
. The regex /CI: x'(\w+)$/
"CI: x'<one or more word characters><end of line>".
The parens around the \w+ capture that to the variable "$1". And that
is going to be the code you're looking for. So in my example.. $1 == "503E". And for any line, it's going to equal whatever is between "x'" and the end of the line.
Hope that clairifies things. And also.. read all of perlre. All of this will be much clearer, and you're probably completely rewrite your script as a result of learning what you can do with regular expressions.