Like certain control panel like Cpanel or VestaCP, once new user created, it automatically adduser into linux. The purpose to do this is to monitor resource usage by each wordpress multi user.
How to do the same just using Wordpress Multisite to automate adduser (on linux) when add new user site?
It will be a problematic thing to do as it will require you to let the webserver run scripts as a system root. It is somewhat hard and requires a lot of thinking security wise about the implications of letting a web server do it.
But you are spared of all that thinking ;) as your scheme is not practical as wordpress MU always runs as the webserver user and you will not be able to associate resource usage with different system users. To actually achieve what you want you will need to create separate wordpress install for each new user.
