Education is a good thing, regardless!
It is a bit amazing that BSD grep, which was pretty open source, did not do
things like Linux, but maybe they licensed the SVR2 grep and built on that.
There might be three or more variations in grep? Did grep change between 1984
and 1988? The differences in OS support are not relevant to a user process
like grep unless it changes a system call or a shared library such as regex
parsing.
On Wednesday, October 8, 2025 at 04:55:42 AM EDT, [email protected]
<[email protected]> wrote:
"David G. Pickett" via Bug reports for GNU grep <[email protected]> wrote:
> Wow, so many UNIX ancestral trails, so is MAC OS really a derivative of
> AT&T System 5 V 4?
This is way off topic, but...
The answer is most likely "no". I suspect that the last Unix Apple
licensed would have been System V Release 2.
The macOS kernel is based on Mach, developed at CMU in the 1980s
by taking BSD Unix and replacing the memory management code and
adding new kinds of IPC. ("Accent on a Vax", for those who
remember such things.)
The macOS user land is from FreeBSD. The man page most likely
indicates that the egrep command itself originated in AT&T Unix,
but it's a good bet that the current macOS egrep code is from FreeBSD.
HTH,
Arnold
