6.2.2.2 Line Endings

When you open a file, Emacs will determine the line endings used.

If the file uses DOS or UNIX line endings, they will be preserved when you open and save a file.

The modeline will tell you what line ending you are using:

U:**-  helloworld.c       92% of 5k   ...

The : means it’s UNIX-style line endings. For DOS it would say ‘(DOS)’.