Running a process as another (non-root) user

FROM : Adrian Ross
DATE : Tue Jan 29 09:09:57 2008

Hello,

I'd like to be able to launch a process running as a particular user - 
a different user from the one running the current process. The current 
process is not running as root. I have the user name and password.

I've got as far as being able to create a valid AuthorizationRef from 
the user name and password; I'm asking for the right 
"system.login.tty" to check if they're valid. It'd be good to be able 
to use this to kick off the new process if possible.

AuthorizationExecuteWithPrivileges doesn't do me much good as that 
runs a process as root - not what I want. I also don't want to have to 
authorise as root or admin to get the process launched.

Any way to do this with just the user name and password of the target 
user? An NSTask with "su - c" doesn't seem very elegant.

Adrian