How to grep such that you search only in a list of files

Question

I have a list of files in a file called scripts.txt

I want to grep for "runcob" only in the files contained in scripts.txt. I dont want to grep in other files that are not contained in scripts.txt. How do I do so. Please help. I am planning to use ksh if we need a script for this

Answer 1

Loop over the list of files and grep:

while read -r file; do
  grep runcob "${file}"
done < scripts.txt

Answer 2

This is why we have xargs.

xargs grep 'runcob' <scripts.txt

Answer 3

If the filenames do not contain any spaces, it could be as simple

grep runcob $(cat scripts.txt)