Use with-temp-file To Write To A File In Emacs

Quick example of how to write out to a file by making a temporary buffer. You write whatever contents you want to the tmp buffer which then outputs to the file and drops the temporary buffer when it's done.

(with-temp-file "test-file.txt"
  (insert "here is some stuff")
  (insert "\n")
  (insert "and some more stuff")