ServerScan | concurrency network scanning and service detection tool | Security Testing library

The better question would be to ask how to get Perl's grep to do what you wanted. It is almost always a better route to write Perl code instead of creating a whole new shell process to do something simple like this. I am certain it is possible, but I cannot correct your misconceptions if you don't explain

The problem is that you don't use chomp to remove the line endings from the records you read from either of the files. Putting a newline in the middle of a shell command will terminate the command at that point, so it looks like grep -i '$server

I would build a hash of blacklisted servers, and check it for each server in the list

The code would look something like this. It uses the case folding fc operator to compare case-insensitively, and so requires the feature to be enabled