Rename multiple file with no extensions?

Question

I have multiple files all named

seperate1
seperate2

etc. How do I rename them all to have the extension .csv?

Answer 1

If there are only files which shall be renamed:

for file in *; do
  mv "$file" "${file}.csv"
done

If there are files with a dot which must be excluded:

for file in *; do
  [[ $file == *.* ]] && continue
  mv "$file" "${file}.csv"
done

Or with shopt -s extglob:

for file in +([^.]); do
  mv "$file" "${file}.csv"
done