Linux User and Group Management Commands

Overview

Linux provides a set of commands for managing users and groups. These commands allow you to create, modify, delete, and view users and groups on the system. This document covers basic and commonly used user and group management commands.

User Management

adduser or useradd

Creates a new user.

sudo adduser <username>
# or
sudo useradd <username>

Example

sudo adduser john
# Creates a new user named 'john'

usermod

Modifies an existing user's account details.

sudo usermod <options> <username>

Example

sudo usermod -aG sudo john
# Adds the user 'john' to the 'sudo' group

deluser or userdel

Deletes a user account.

sudo deluser <username>
# or
sudo userdel <username>

Example

sudo deluser john
# Deletes the user 'john' but keeps the home directory

passwd

Changes a user's password.

sudo passwd <username>

Example

sudo passwd john
# Prompts to change the password for the user 'john'

id

Displays information about a user.

id <username>

Example

id john
# Output: Displays user ID (UID), group ID (GID), and group memberships for 'john'

whoami

Displays the username of the current user.

whoami

Example

whoami
# Output: Displays the current logged-in username

Group Management

addgroup or groupadd

Creates a new group.

sudo addgroup <groupname>
# or
sudo groupadd <groupname>

Example

sudo addgroup developers
# Creates a new group named 'developers'

delgroup or groupdel

Deletes a group.

sudo delgroup <groupname>
# or
sudo groupdel <groupname>

Example

sudo delgroup developers
# Deletes the group named 'developers'

gpasswd

Modifies group memberships and settings.

sudo gpasswd -a <username> <groupname>

Example

sudo gpasswd -a john developers
# Adds the user 'john' to the 'developers' group

groups

Displays the groups that a user belongs to.

groups <username>

Example

groups john
# Output: Displays the groups that the user 'john' belongs to

View Users and Groups

getent

Displays entries from databases configured in /etc/nsswitch.conf, including users and groups.

getent passwd

Example

getent passwd
# Output: Displays all user accounts in the system

cat /etc/passwd

Displays the contents of the user account database file.

cat /etc/passwd

Example

cat /etc/passwd
# Output: Displays user account information including username, UID, GID, home directory, and shell

cat /etc/group

Displays the contents of the group database file.

cat /etc/group

Example

cat /etc/group
# Output: Displays group information including group name, GID, and group members

Summary

Linux offers a range of commands for managing users and groups, including creating, modifying, and deleting accounts and groups. Understanding these commands helps in effectively managing user and group permissions on a Linux system. For more detailed information on each command, refer to the Linux manual pages.