How do I include a blank line between files I'm concatenating with “cat”?

Question

I want to cat all the files in a directory, but include some spacer between each one.

Answer 1

echo "" > blank.txt
cat f1.txt blank.txt f2.txt blank.txt f3.txt

To handle all of the files in a Directory (assuming ksh like Shell)

for file in * ; do
   cat $file >> result.txt
   echo "" >> result.txt
done