Chris Siebenmann with another interesting look at a tiny detail of UNIX history.
A few years ago I wrote about the divide in chown() about who got to give away files, where BSD and V7 were on one side, restricting it to root, while System III and System V were on the other, allowing the owner to give them away too.
[….]The answer is that the restriction was added in V6, where the V6 chown(2) manual page has the same wording as V7. In Research Unix V5 and earlier, people can chown(2) away their own files; this is documented in the V4 chown(2) manual page and is what the V5 kernel code for chown() does. This behavior runs all the way back to the V1 chown() manual page, with an extra restriction that you can’t chown() setuid files.
↫ Chris Siebenmann
The deeper levels of this particular rabbit hole need more exploring, though, as eventually Siebenmann hits a roadblock when trying to figure out why, exactly, the restriction was added, and why certain versions chose to not adopt the new restriction. This may be part of the lore of UNIX we won’t uncover, until one of the people involved speaks up.
