Print line

Hello!

When I search a string in several .txt datas I get the output of the files the string was found. Let's say I find 10 files with the string I was looking for.
Now I want to use the output files (only the output files, not all files!) and print the first line of all the output files.
Is there a way to do this? The search works fine but I can't figure out how to use the output automatically without typing all the output names manually in.

Thanks