UID and GID: The Basics of Linux User Admin

“Whether your Linux box has hundreds of users or just one
account for you and one for your dog it is important to understand
how Linux user accounts work. There are GUI tools for this within
GNOME and KDE but here we lift the lid on the bonnet to show what
really makes a user exist, and what these commands are doing to
your filesystem.

“Being a multi-user system, Linux can allow many people to use
the one computer. Each of these people is known as a ‘user’ of the
system. In fact, there may be many other users in Linux who are not
even people–these might be programs running, like a Web server,
that execute as a special user with limited access to the
system…”

Complete
Story