For more information about users and groups, and tools to manage them, refer to the following resources.
Related man pages — There are a number of man pages for the various applications and configuration files involved with managing users and groups. Some of the more important man pages have been listed here:
man chage — A command to modify password aging policies and account expiration.
man gpasswd — A command to administer the /etc/group file.
man groupadd — A command to add groups.
man grpck — A command to verify the /etc/group file.
man groupdel — A command to remove groups.
man groupmod — A command to modify group membership.
man pwck — A command to verify the /etc/passwd and /etc/shadow files.
man pwconv — A tool to convert standard passwords to shadow passwords.
man pwunconv — A tool to convert shadow passwords to standard passwords.
man useradd — A command to add users.
man userdel — A command to remove users.
man usermod — A command to modify users.
man 5 group — The file containing group information for the system.
man 5 passwd — The file containing user information for the system.
man 5 shadow — The file containing passwords and account expiration information for the system.
Red Hat Enterprise Linux Introduction to System Administration; Red Hat, Inc. — This companion manual provides an overview of concepts and techniques of system administration. The chapter titled Managing User Accounts and Resource Access has great information pertaining to user and group account management.
Red Hat Enterprise Linux System Administration Guide; Red Hat, Inc. — This companion manual contains more information on managing users and groups as well as advanced permission configuration using ACLs. Refer to the chapters titled User and Group Configuration and Access Control Lists for details.
Red Hat Enterprise Linux Security Guide; Red Hat, Inc. — This companion manual provides security-related aspects of user accounts, namely choosing strong passwords.