The Heirloom Project

Update: there’s a fork called heirloom-ng that is actually still somewhat maintained and contains some more changes and modernisations compared to the old version.

The Heirloom Project provides traditional implementations of standard Unix utilities. In many cases, they have been derived from original Unix material released as Open Source by Caldera and Sun.

Interfaces follow traditional practice; they remain generally compatible with System V, although extensions that have become common use over the course of time are sometimes provided. Most utilities are also included in a variant that aims at POSIX conformance.

On the interior, technologies for the twenty-first century such as the UTF-8 character encoding or OpenType fonts are supported.
↫ The Heirloom Project website

I had never heard of this before, but I like the approach they’re taking. This isn’t just taking System V tools and making them work on a modern UNIX-like system as-is; they’re also improving by them adding support for modern technologies, without actually changing their classic nature and the way old-fashioned users expect them to work. Sadly, the project seems to be dead, as the code hasn’t been altered since 2008. Perhaps someone new is willing to take up this project?

As it currently stands, the tools are available for Linux, Solaris, Open UNIX, HP-UX, AIX, FreeBSD, NetBSD, and OpenBSD, but considering how long the code hasn’t been touched, I wonder if they still run and work on any of those systems today. They also come in various different versions which comply with different variants of the POSIX standard.