From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Tolpin <dvd@davidashen.net>
Message-Id: <200403170854.i2H8sk2J083766@adat.davidashen.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Novice question - run as other
In-Reply-To: <fbca9b00662c47f7e01281af87e28e1e@9netics.com>
Date: Wed, 17 Mar 2004 12:54:46 +0400
Topicbox-Message-UUID: 32b625f8-eacd-11e9-9e20-41e7f4b1d025

> >> > a program from a shell script and change the user it runs as.
> >>
> >> The security model doesn't allow this. Perhaps by running it as a service
> >> on a cpu.  Check /sys/src/cmd/auth/cron.c and cap(3).  For somethings
> >> you can cpu over and change to a different uid:
> > 
> > The following works:
> ...
> > 	fd>=0 && (write(fd,"none",strlen("none"))!=-1)
>
> That's not what you asked.
>

? Is none not user?

cpu% grep none /adm/users
0:none:adm

cpu% none
cat /env/user
none

I want a program to run as a different user. From C, it means opening
'#c/user' and writing the user's name there. The security model is
a separate issue, the call either succeeds or fails, 
but it is a consequence of security limitations, and not of the API.

My question was how to do the same from rc. 

@{echo -n none > '#c/user' ; while() {sleep 1} }

succeeds but does not change the owner of the process. Why?

David