You want to make use of the files changed in conditionals to block or allow certain steps.
git show will show the latest changes. Combined with Grep, this will allow us to see if a certain file changed, and based on that set a variable.
if git show | grep filechanged.txt; then cf_export variable=true else cf_export variable=false
We suggest putting this in a bash script rather than inline. You can then use this variable in conditionals.
If you are looking for an all-or-nothing approach, we suggest using the glob expression checker as part of your trigger. If the logic grows to be significantly different, we would suggest relying on multiple pipelines instead.