[TUHS] Additional groups and additional directory permissions

Arthur Krewat krewat at kilonet.net
Fri Aug 2 22:45:51 AEST 2019

On 8/2/2019 4:35 AM, arnold at skeeve.com wrote:
> [Subject line changed]
> Hi.
> Arthur Krewat <krewat at 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.
>> 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.
>> I have no idea what the timeline is for either of these features :)
> Timeline is late 80s, SunOS 4.0, I believe. (Larry? :-)
> These ideas later propogated into SVR4 / Solaris, Linux and most (if not all)
> the other proprietary Unixes.

Makes a lot of sense. I just fired up my Consensys SVR4.2 VirtualBox 
guest, and sure enough, neither the sticky bit, nor setgid work on 

My first commercial experience with UNIX as a consultant was SunOS. I 
had worked on Version 6 earlier, but that was purely personal and never 
more than messing around with a uVAX a friend had brought home from work.

thanks for the info!
art k.

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