I had encountered sqlcl before, but it requires the JVM, and I don't believe it is open source. With usql, it's open source (MIT), already works with more databases than sqlcl does, and very soon I will have built releases for Windows, OSX, and Linux that one will simply be able to download a single, relatively small (roughly 8 megs) binary and be able to work with any SQL database using the exact same command-line interface for each.