Chapter 5. Users and Groups
Control of users and groups
is a core element of Red Hat Linux system administration.
Users can be either people, meaning accounts tied
to physical users, or logical users, meaning accounts which exist for
specific applications to use. Both types of users have a unique
User ID (UID) and
Group ID (GID).
Groups are logical expressions of
organization. Groups tie users together, giving them permissions to read,
write, or execute files.
When a file is created it is assigned a user and group. It is also
assigned separate read, write, and execute permissions for the file's
owner, group, and everyone else. The user and group of a particular file,
as well as the access permissions on the file, can be changed by root or,
in most cases, by the creator of the file.
Proper management of users and groups and effective management of file
permissions, are among the most important tasks a system administrator
undertakes in the course of his duties.
Tools for User and Group Creation
Managing users and groups can be a tedious task, but Red Hat Linux provides a
few tools and conventions to make management easier for administrators.
You can use tools like useradd or
groupadd to create new users and groups from the
shell prompt. But an easier way to manage users and groups is through
the graphical application,
User Manager. For more information on
User Manager, refer to the
Official Red Hat Linux Customization Guide.
In the Section called User Private Groups further discuss file
permission concepts and will walk through command line steps for managing
users.
