Add a newline only if it doesn't exist

Question

I want to add a newline at the end of a file only if it doesn\'t exists, this is to prevent multiple newlines at the end of the file.

I\'m hoping to use sed. Here\'s the

Answer 1

Using awk :

awk '/^$/{f=1}END{ if (!f) {print "\r"}}1' inputfile

Match blank line ^$(just like you did) and set up a flag. If flag is not set at the end, place newline character.

Note: that \r is in OS X. Use \n for other.