About a third of a century ago, I read the original source code to the Linux ps program that worked by reading kernel memory from a setuid root program, used that to enhance the brand-new /proc filesystem to support all the features I now knew ps might need, and wrote a brand-new version of ps. I added features I'd wanted forever on the VAX 11/780 I was using at the time, like built-in sorting instead of piping through sort or awk, and at least trying to fully honor both BSD and System V command-line arguments. I called it "procps" to distinguish it from the original "kmem" ps.
As far as I know, none of my original code survives. I think it's been re-written at least once, maybe twice by now. This is clearly the procps of Theseus.
But it's still called "procps" in Linux distributions, which I have to imagine confuses newcomers. "Why do I have to install procps to get the ps command?"
