Linux User and Group Management: A Comprehensive Guide

The essential commands for creating, modifying, and deleting user accounts, as well as managing user privileges and groups.

User Management:

1. Creating a new user:

   sudo useradd username
   

   Set the user’s home directory and shell:

   sudo useradd -d /home/username -s /bin/bash username
   

2. Setting a password for the user:

   sudo passwd username
   

3. Deleting a user:

   sudo userdel -r username
   

4. Modifying user properties:

   sudo usermod -g newgroup -aG group1,group2 -d /new/home/directory -s /bin/newshell username
   

5. Listing all users:

   getent passwd
   

6. Changing to another user:

   su - username
   

7. Granting sudo privileges:

   sudo visudo
   

   Add the following line:

   username  ALL=(ALL:ALL) ALL
   

8. Locking and unlocking user accounts:

   sudo passwd -l username  # lock
   sudo passwd -u username  # unlock
   

Group Management:

1. Creating a new group:

   sudo groupadd groupname
   

2. Adding a user to a group:

   sudo usermod -aG groupname username
   

3. Removing a user from a group:

   sudo deluser username groupname
   

4. Listing all groups:

   getent group
   

5. Modifying group properties:

   sudo groupmod -n newgroupname oldgroupname
   

   Add or remove a user from a group:

   sudo gpasswd -a username groupname  # Add user to group
   sudo gpasswd -d username groupname  # Remove user from group
   

6. Deleting a group:

   sudo groupdel groupname
   

7. Checking a user’s groups:

   groups username
   

8. Changing the primary group of a user:

   sudo usermod -g newprimarygroup username
   

These commands provide a comprehensive overview of user and group management on a Linux system. Whether you’re creating new users, modifying user properties, managing groups, or adjusting user privileges, these commands will help you effectively administer your Linux environment.