Convert SageNB (.sws) worksheets to Jupyter (.ipynb) worksheets

There are several ways to go, depending on whether you want to convert SageNB worksheets from your SageNB collection (they live in the .sage folder in your home folder), or .sws files that exist elsewhere in your filesystem.

For a SageNB .sws worksheet located somewhere visible in your file system, you could convert it to reStructuredText (.rst) using sws2rstand then convert the .rst file to a Jupyter .ipynb worksheet with rst-to-ipynb.

Or you could upload it to your SageNB collection, as indicated by @Iguananaut (run sage -n sagenb, upload the .sws files to your SageNB collection), then use the exporter (launch it by running sage -n export in a terminal) which will offer to export all SageNB worksheets in your SageNB collection to Jupyter worksheets.