4 Aug
2019
4 Aug
'19
8:40 a.m.
arnold(a)skeeve.com <arnold(a)skeeve.com> wrote:
> Arthur Krewat <krewat(a)kilonet.net>:
> > There's also the setgid bit on directories, that when files are created,
> > they will be in the group that the parent directory has on it.
>
> IIRC this was a Sun invention. It was in SunOS 4.x, and may even have
> been in SunOS 3.x.
Tony Finch <dot(a)dotat.at> wrote:
When Bill Joy added the "multi-group stuff"
to BSD all directories became
implicitly set-gid:
Yes. But the commercial world had backwards compatibility to worry about.
Thus the setgid bit on directories. I'm no longer sure who first came
up with it.
As I understand it, when group support was improved in
System V they did
not change creat() to match BSD but instead used the directory set-gid bit
to provide opt-in BSD semantics. I don't know if this was in Solaris or
earlier?
Correct, but not sure when it was first done.
Also, I don't think it's been mentioned, but
there's the setuid bit on
directories - otherwise known as the sticky bit. When set, even if you
have rights to "write" the directory (meaning, delete files), you can't
delete those owned by other users. Useful for /tmp
Also a SunOS invention, IIRC.