Difference Between User And Group Management In Linux

Difference between user and group management in linux

While User and Group management are two sides of the same administrative coin, they serve fundamentally different objectives in a Linux system. Think of a User as an individual identity and a Group as a permission-sharing bucket.

Core Definitions

• User Management: User management is centered on the individual. It defines login users, their passwords, home directories, and environment settings (like shell).

• Group Management: Roles are the main emphasis of group management. It is used to bundle numerous users together so that an administrator can apply the same set of rights to everyone in that bundle simultaneously.

Also read about Explain User And Group Management In Linux With Examples

User Vs Group management in linux

Feature	User Management	Group Management
Primary Goal	Authentication (Who are you?)	Authorization (What can your team do?)
Identification	Unique UID (User ID)	Unique GID (Group ID)
Home Directory	Usually has /home/username	Does not have a directory
Filesystem	Owns files/folders	Grants access to files/folders
Storage File	/etc/passwd	/etc/group
Primary Command	useradd, usermod, userdel	groupadd, groupmod, groupdel

How They Communicate

In Linux, every User must belong to at least one group (their Primary Group, commonly named the same as the username). A user may, nevertheless, also belong to numerous Secondary Groups.

The Workflow Example:

• You create 5 Users (Alice, Bob, Charlie, etc.).
• You establish a single group named accounting.
• The accounting group is expanded to include all five users.
• Instead of altering permissions on a folder 5 times, you modify it once for the accounting group.

Why Use Both?

Efficiency: If a new person joins the marketing team, you don’t need to manually give them access to 100 separate folders. You simply create their User account and add them to the marketing Group.

Security: If a person departs the organization, their access is immediately terminated by deleting their account, but the group is still accessible to the other team members.

Organization: User management handles personal settings (such a custom desktop wallpaper), while Group management manages shared resources (like access to a printer or a shared database).

Security Context

• User-level “My documents” are separated from “Your documents.”
• Group level: Shields “The Finance Department’s files” from “The Engineering Department’s files.”

Also read about Explain File Permissions In Linux & Ownership With Examples

User and group management in linux interview questions

How do you create a user in Linux?

Using the useradd command:

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useradd john

This creates a user but does not set a password.

To set a password:

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passwd john

How do you delete a user?

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userdel john

To remove the user and home directory:

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userdel -r john

How do you modify a user?

The usermod command is used.

Change username:

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usermod -l newname oldname

Change home directory:

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usermod -d /home/newdir -m john

Add user to a group:

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usermod -aG developers john

Also read about How To Create A Startup Service In Linux Using Systemd

How do you create and manage groups?

Create a group:

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groupadd testers

Delete a group:

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groupdel testers

Modify a group name:

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groupmod -n qa testers

What is primary and secondary group?

Primary group

This is the main group assigned to a user when the account is created.

Secondary group

Additional groups a user belongs to.

Check groups:

bash

groups john

How do you check current logged-in user?

bash

whoami

Or:

bash

who

How do you list all users in Linux?

bash

cat /etc/passwd

Or:

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getent passwd

What is UID and GID?

• UID (User ID): A unique number assigned to each user.
• GID (Group ID): A unique number assigned to each group.

Linux internally identifies users and groups using IDs, not names.

What is the su command?

The su command allows switching to another user.

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su root

This switches to the root user.

What is the sudo command?

sudo allows a normal user to execute commands with root privileges.

Example:

bash

sudo apt update

Only users listed in /etc/sudoers can use this.

Also read about What Is The Difference Between Systemd And Systemctl?

What is the id command?

Displays user identity.

bash

id john

Shows UID, GID, and groups.

How do file permissions relate to users and groups?

Every file in Linux has:

• An owner (user)
• A group
• Permissions for others

Example output:

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-rwxr-xr-- 1 john developers file.txt

Meaning:

• Owner: john
• Group: developers
• Others: rest of users

What is the purpose of /etc/login.defs?

It controls default settings for user accounts, such as:

• Password expiry
• Minimum UID
• Home directory settings

What is newgrp?

newgrp allows a user to switch their primary group temporarily.

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newgrp developers

What is the difference between useradd and adduser?

• useradd: Low-level command, minimal setup.
• adduser: High-level interactive command (available in Debian-based systems).

Common interview scenario questions

Q: How do you give a user access to a shared folder?

Answer:

Create a group, add users to the group, and assign folder permissions to the group.

Q: How do you lock a user account?

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passwd -l john

Q: How do you unlock a user account?

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passwd -u john

Also read about Basic Linux Commands For Beginners With Easy Examples