Account Creation and Deletion

Cybersecurity Linux Lesson 2.2.1

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Creating User Accounts

To create a new user account, we use the command useradd followed by the username.
Format:

sudo useradd <options> <new username>

For example:

sudo useradd john

Adding More Information

You can change or add info to a user account with the usermod command. Format:

sudo usermod <options> <username>  

For example:

sudo usermod –c “John Smith” john  

This will set the user’s comment, which is often a full name, to John Smith.

Or

sudo usermod –g Sales john

This will add the john account into the Sales group.

Adding Groups

The groupadd command in Linux is used to create a new user group on the system.
Format:

sudo groupadd <options> <new group name> 

For example:

sudo groupadd mygroup  

Groups can be used to manage users with similar permissions or rights.

Modifying Groups

Groups can by modified with the groupmod command.
Format:

sudo groupmod <options> <group name>  

For example:

sudo groupmod –n supergroup mygroup  

This would change the name of an existing group from “mygroup” to “supergroup”.

Deleting User Accounts and Groups

To delete a user account, use the userdel command followed by the username. For example:

sudo userdel john  

To delete the account plus their directories use the –r option:

sudo userdel -r john  

Similarly groupdel deletes entire groups.

sudo groupdel mygroup

Check User Information

There are commands you can use to quickly check system information about a user.
The id command displays the user’s unique ID, their groups and other user account properties. Use the following command:

id john  

The who command displays list of logged-in users.
The w command provides detailed information about logged in users including the time they logged-in and the processes they are running