nb is a command line note-taking, bookmarking, archiving, and knowledge base application with:
- plain-text data storage,
- encryption,
- filtering and search,
- Git-backed versioning and syncing,
- Pandoc-backed conversion,
- global and local notebooks,
- customizable color themes,
- extensibility through plugins,
and more, all in a single portable, user-friendly script.
See https://xwmx.github.io/nb/ for screenshots etc, it looks cool! No, I haven't tried it (as of writing this).