Comment /rdb (Score 2) 383
/rdb - definitely not free, but a fascinating use of the shell and shell extensions as a database management system. Don't know if it's even still available. The NoSQL developer Carlo Strozzi said that he was inspired by it. Used to be at http://www.rsw.com./ An excellent white paper, "The UNIX Shell As a Fourth Generation Language" describes it, and there was a book too - "Unix Relational Database Management". I used it nearly 20 years ago for a retirement home's database when their DOS/dBase system broke down. Slackware Linux version 1 ran fine on their old PC. In fact, that was my first Linux kernel compilation.