Chapter 33. Users and Groups

Chapter 33. Users and Groups

33.1. User and Group Configuration
33.1.1. Adding a New User
33.1.2. Modifying User Properties
33.1.3. Adding a New Group
33.1.4. Modifying Group Properties
33.2. User and Group Management Tools
33.2.1. Command Line Configuration
33.2.2. Adding a User
33.2.3. Adding a Group
33.2.4. Password Aging
33.2.5. Explaining the Process
33.3. Standard Users
33.4. Standard Groups
33.5. User Private Groups
33.5.1. Group Directories
33.6. Shadow Passwords
33.7. Additional Resources
33.7.1. Installed Documentation

The control of users and groups is a core element of Red Hat Enterprise Linux system administration.

Users can be either people (meaning accounts tied to physical users) or accounts which exist for specific applications to use.

Groups are logical expressions of organization, tying users together for a common purpose. Users within a group can read, write, or execute files owned by that group.

Each user and group has a unique numerical identification number called a userid (UID) and a groupid (GID), respectively.

A user who creates a file is also the owner and group owner of that file. The file is assigned separate read, write, and execute permissions for the owner, the group, and everyone else. The file owner can be changed only by the root user, and access permissions can be changed by both the root user and file owner.

Red Hat Enterprise Linux also supports access control lists (ACLs) for files and directories which allow permissions for specific users outside of the owner to be set. For more information about ACLs, refer to Chapter 8, Access Control Lists.

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