GNU recutils

Quote:

There are hundreds of cool command line tools that have been made over the years built on the unix philosophy. Plain text is powerful, ubiquitous, and human-centric. It was also the only option for computing for quite a while. Itis no surprise that some of the most sophisticated tools are focused on it. One such package is GNU Recutils, a set of tools and libraries to access human-editable, plain text databases called recfiles. Using plain text that is primarily human-readable as a database is just frankly cool as hell.

From: https://labs.tomasino.org/gnu-recutils/

https://www.gnu.org/software/recutils/

Recutils reminds me a little of RDB:

RDB -- A UNIX Command-Line Database by Mark Pruett

Portable Database Management with /rdb

Public domain RDB clone