/rdb is a high-performance relational database management and application development system designed for Unix and implemented as a suite of 131 shell level commands. Unlike other fourth generation systems, /rdb is an extension of the Unix environment, making available the full power of Unix during application development and usage. Database utilities such as sorttable, jointable, row, column and compute are programs invoked by the shell which read tables from the standard input and write tables to the standard output. All of the relational operators are included, as well as several indexing methods, a vi-like forms editor, a powerful report generator, menus, and a number of data transformation utilities. /rdb stores tables in efficient variable length ASCII files, making them accessible to ordinary Unix commands.

A most exciting aspect of this pipeline paradigm is its inherent parallelism: without change, /rdb applications enjoy efficiencies that grow almost linearly with the number of processors in SMP systems.

/rdb means freedom from the software prisons created by proprietary interfaces that require learning yet another language or way of thinking.

The UNIX Shell as a 4GL is a more detailed description, including comparisons with other database systems and /rdb examples.