Delete all lines not containing a specified string?

Also from notepad years ago. How in atom to delete all lines not containing a specified string? Thanks

I also need to delete all blank lines.

With this package ? https://atom.io/packages/delete-whitelines

Thanks for replying. I tried that earier it and it doesn’t work for me - some popup window is displayed. I dug on my old Windows laptop, downloaded Notepad++ and got what I needed.

The packages are made by contributors and are generally available on GitHub to fork and PR