I guess that a lot of atom users are coming from sublime, and we tend to expect some keyboard shortcut like the split-selections-into-lines.

On mac os it's the same keybinding than sublime for split-selections-into-lines, but not on Linux and nor Windows.

I had to add the following lines to my keymap.cson:

'.platform-linux atom-text-editor':
  'ctrl-shift-L': 'editor:split-selections-into-lines'