How to Manage Users and Groups in Ubuntu

Edited 3 weeks ago by ExtremeHow Editorial Team

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Managing users and groups in Ubuntu is an essential skill for both administrators and users. It allows effective management of system access and permissions. In Linux systems, including Ubuntu, everything revolves around users and groups. This comprehensive guide will introduce you to various ways to manage users and groups on Ubuntu systems.

Understanding users and groups in Ubuntu

Before diving into user and group management, it is important to understand what users and groups are and why they are important.

A user in Ubuntu is an entity that can access system resources and has permissions defined by the system administrator. Each user has a unique user ID (UID), a username, and user-specific settings that are stored in their home directory.

A group in Ubuntu is a collection of users. Groups are used to simplify the management of permissions. Instead of setting individual permissions for each user, an administrator can set them for a group and assign them to users.

Basic user management

Create a new user

To create a new user in Ubuntu, you can use adduser command. This is a user-friendly command that will ask for information such as the user's full name, room number, and other optional details.

Open the terminal and type the following command:

sudo adduser newusername

Replace newusername with the name of the new user you want to create. You will be asked to set a password and provide additional information.

Deleting a user

To delete a user, use the deluser command. Be careful when using this command as it will delete the user's login without confirmation.

To delete a user, use the following command:

sudo deluser username

If you want to delete the user's home directory and mail spool, use:

sudo deluser --remove-home username

Modify user information

Modifying user information includes changing the user's password and other details. Here are the commands you need:

• Change password: Use passwd command to change a user's password.

  sudo passwd username

• Change user information: Use the chfn command.

  sudo chfn username

Group management

Create a new group

To create a new group in Ubuntu use addgroup command:

sudo addgroup newgroupname

Replace newgroupname with the desired group name.

Adding users to groups

Once groups are created, you can add users to them using usermod command with the -aG option. This adds the user to the group without removing them from other groups.

sudo usermod -aG groupname username

Replace groupname with the name of the group and username with the user you want to add.

Removing users from groups

If you need to remove a user from a group, use the gpasswd command:

sudo gpasswd -d username groupname

This will remove the specified user from the specified group.

Understanding user and group files

User and group information on a Linux system is stored in specific files. Understanding these files is important to effectively manage users and groups.

• /etc/passwd: This file stores essential information about user accounts, such as username, UID, GID, and home directory.
• /etc/shadow: This file stores secure user passwords.
• /etc/group: This file contains group information, such as group name, GID, and member list.

Permissions and ownership

Understanding permissions and ownership is important in user and group management. In Ubuntu, every file and directory has three types of permissions:

• Read (r): Permission to read the file or directory.
• Write (w): Permission to write or modify a file or directory.
• Execute (x): Permission to execute a file or traverse a directory.

Permissions are assigned to three different classes of users:

• User: The owner of the file.
• Group: The group assigned to the file.
• Other: Everyone else.

To change file permissions, use the chmod command. This command modifies the permission settings of a file or directory. Its syntax is:

chmod permissions filename

To change file ownership, use the chown command. The syntax of chown is:

sudo chown user:group filename

Advanced user and group management

Creating a system user

System users are special types of users that are used to run services and applications. They often do not have login rights. To create a system user, use useradd command with options to disable the home directory and login shell:

sudo useradd -r -s /usr/sbin/nologin sysusername

Setting group permissions

Groups can also be given specific permissions using the chmod command. For example, to give a group write permissions, you could use:

sudo chmod g+w filename

Managing default user and group configuration

Default user settings are stored in /etc/default/useradd and /etc/login.defs files. Administrators can modify these files to change the default UID, GID, and other user account settings.

Utilities for user and group management

There are many utilities available for managing users and groups in Ubuntu. Some of these widely used utilities are as follows:

• id: Used to display the user ID (UID) and group ID (GID) of a user.

  id username

• Groups: Lists all the groups a specific user belongs to.

  groups username

• Finger: Provides detailed information about the user.

  finger username

Conclusion

Managing users and groups in Ubuntu may initially seem complicated, but with familiarity, it becomes second nature. Understanding how to create, modify, and delete users and groups, modify permissions and ownerships, and effectively manage the system allows for robust and secure system administration. By mastering the commands and concepts outlined in this guide, you will be equipped to efficiently handle user and group management on Ubuntu.

Remember that careful management and planning is vital to ensure the safety and efficiency of the systems you administer. Always double-check your orders and make sure the operation is necessary before executing them.

Happy managing!

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