the file filesystem: mount semi-structured data (like JSON) as a Unix filesystem
The Symbolic, Mechanized, Observable, Operational SHell: an executable formalization of the POSIX shell standard.
The dash shell as a linkable library. Tracks https://git.kernel.org/pub/scm/utils/dash/dash.git, with extended interfaces, bindings for Python and OCaml, and tools for generating JSON representations of shell scripts.