The control of users and
groups exists at the core of Red Hat Linux system
administration.
Users can be either people (accounts tied to a
physical user) or logical users (accounts that exist for applications so
that they can perform specific tasks) . Both types of users have a
User ID (which is usually unique) and
Group ID.
Groups are logical expressions of
organization. Groups form the foundation of tying users together and
giving them permissions to read, write, or execute a given file.
Any file created is assigned a user and group when it is made. It is also
assigned separate read, write, and execute permissions for the file's
owner, the group assigned to the file, and any other users on that
host. The user and group of a particular file, as well as the permissions
on that file, can be changed by root or, to a lesser extent, by the
creator of the file.
Proper management of users and groups, as well as assigning and revoking
permissions, is one of the most important tasks of any system
administrator.
Managing users and groups has traditionally been tedious, but Red Hat Linux
provides a few tools and conventions to make users and groups easier to
manage.
While you can use useradd to create a new user from
the shell prompt, a popular way to manage users and groups is through
redhat-config-users (refer to the
Official Red Hat Linux Customization Guide for more information).
