With RubyMine, you can set up line separators (line endings) for newly created files, and change line separator style for existing files.
Set up line separators for new files
Check line ending style for the current file
The line ending style applied to the current file is indicated in the status bar, for example:
Change line separator for a file currently opened in the editor
From the main menu, chooseand choose a line ending style from the list.
Change line separator for a file or directory selected in the Project view
Select a file or directory in the Project tool window Alt+1.
Note that if a directory is selected, the line ending style applies to all nested files recursively.
From the main menu, choose, and then select a line ending style from the list.