Managing users and groups is a fundamental aspect of Linux system administration. This module will cover the essential commands and concepts needed to effectively manage users and groups on a Linux system.

1. Users and Groups:

   • Users: Individual accounts that can log into the system.
   • Groups: Collections of users that share certain permissions.

2. User Management:

   • Creating, modifying, and deleting user accounts.
   • Managing user passwords and account information.

3. Group Management:

   • Creating, modifying, and deleting groups.
   • Adding and removing users from groups.

To create a new user, use the useradd command:

• username: The name of the new user.

Example:

After creating a user, set a password using the passwd command:

Example:

To modify an existing user, use the usermod command. For example, to change a user's home directory:

Example:

To delete a user, use the userdel command:

Example:

To create a new group, use the groupadd command:

Example:

To add a user to a group, use the usermod command with the -aG option:

Example:

To remove a user from a group, use the gpasswd command:

Example:

To delete a group, use the groupdel command:

Example:

1. Create a new user named alice.
2. Set the password for alice to password123.
3. Change alice's home directory to /home/alice_new.
4. Delete the user alice.

Solution:

1. Create a new group named testgroup.
2. Add a user named bob to testgroup.
3. Remove bob from testgroup.
4. Delete the group testgroup.

Solution:

• Forgetting to use sudo: Most user and group management commands require superuser privileges.
• Not using the -aG option: When adding a user to a group, forgetting the -aG option can remove the user from other groups.
• Deleting users without removing their home directories: Use the -r option with userdel to remove the user's home directory as well.

Example:

In this section, you learned how to manage users and groups in Linux. You now know how to create, modify, and delete users and groups, as well as how to manage user passwords and group memberships. These skills are essential for maintaining a secure and organized Linux system. In the next module, we will delve into disk management, where you will learn how to manage storage devices and file systems.