In this article, I am explaining what are users and groups in Linux and how to create users, apply different policies on users and delete them. I am also explaining how to create groups in Kali Linux and how to add users to different groups.
After reading this blog about Users and Groups in Linux you will gain in-depth knowledge about Users and groups in Linux. So Let’s dig in.
So first I am explaining what is “User”?. Just like you create an account in some social media platform to manage all your activities same is the case with Linux, through a user account, you can manage your activities in Linux.
Types of Users in Linux:
There are mainly three types of users in Linux:
- Normal User (Un Privileged User)
- System User
- Root User (Privileged User)
Groups in Linux:
Just like in Whatsapp, we add multiple people to send messages to all people at a time. Same is the case with Linux. In Linux, we create a group, add different users to the group and then implement policy on that group so that that group policy will be implemented on every user present in that group. It will be easy for us to manage different users by adding them into groups.
Users: Stored in /etc/passwd
Passwords /etc/shadow
Groups /etc/groups
Encrypted Group Passwords /etc/gshadow
How to Create a User in Kali Linux?
adduser username
For example:
If we want to add user xyz into your Kali machine then we can type the above command like
adduser xyz
The above command will not only create a user but will also create a home directory for the user and it will follow settings based on the configuration file.
The configuration file is present at
/etc/adduser.conf
You can view it through the cat command like for example
cat /etc/adduser.conf
How to get information about created users?
getent passwd username
for example:
If I want to get information about user xyz then I can type the above command as
getent passwd xyz
this will display details about user and its group.
To get information about all the users
getent passwd
How to change the password for the user?
passwd userName
For example:
if I want to change a password for the user xyz then I can type the above command as
passwd xyz
Changing the users information like Full Name
chfn userName
For example, If I want to change the name for the user xyz in our case then I can type the above command like
chfn xyz
Changing the shell for the user
For example, to change the shell for the user We can use the command like
chsh
Changing the age of the password for user
We can change the age of password for user through chage command.
chage userName
For Example:
If we want to change the age of a command for user xyz then we can type the above command like
chage xyz
When a user login next time, he or she must change the password.
passwd -e userName
For example:
If we want that our user xyz must change the password then he/she want to login next time. Then we can write above command as:
passwd -e xyz
How to disable a user account in Kali Linux?
To disable a user account in Kali Linux then we can type
passwd -l userName
For Example:
If we want to disable user account for xyz user then we can type the above command as:
passwd -l xyz
Now user account is disabled for the user xyz..
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How to delete a user account in Kali Linux?
To delete a user account you can just type the following command as:
userdel userName
for Example:
To delete a user account of xyz user then we can write the above command as:
userdel xyz
How to delete a user account including its home directory and settings.
userdel -r userName
For Example:
userdel -r xyz
How to add group in Kali Linux?
To add group you can type the following command like:
addgroup groupName
For example:
To add a group name abc you can type the above command like:
addgroup abc
How to delete group in Kali Linux?
To delete group in Kali linux type the following command like
delgroup groupName
for example:
If I want to delte a group named abc. I can type the above command like:
delgroup abc
How to set a password for group in Kali Linux?
gpasswd groupName
For Example:
If I want to set a password for group abc then I can type the above command like
gpasswd abc
How to remove password for group in Kali Linux?
gpasswd -r groupName
For example:
If I want to remove a password for group abc then I can type above command like:
gpasswd -r abc
How to add user to a group?
In order to add a user to group we can type
the following command.
sudo usermod -a -G groupname username
For Example:
To add xyz user to group abc we can type above command like:
sudo usermod -a -G abc xyz
-a means that add user to the group without removing it from other existing group.
-G means that it must be followed by 1 or more group name.
How to add user to multiple groups.
To add a user to multiple groups we can use the following command like:
sudo usermod -a -G groupname1, groupname2 Username
How to remove a user from a group?
To remove a user from a group we can use commands like
sudo gpasswd -d username groupname
For Example:
In order to remove a user xyz from group abc we can use the above command like
sudo gpasswd -d xyz abc
xyz user will be removed from group abc.
How to delete a group in Kali Linux?
To delete a group in Kali Linux type the following command.
sudo groupdel groupName
For exampel: To remove group abc we can type the above command like:
sudo groupdel abc
How to view information about groups.
getent group
How to change a user’s primary group?
sudo usermod -g groupName username
For example:
To change a user primary group from abc to def then we can type the above command like:
sudo usermod -g def xyz
Creating User and assinging group in one command
sudo useradd -g users -G wheel,developers nathan
for example:
To add a user jkl and assinging a group abc.
sudo usermod -g users -G Group1,Group2,Group3
How to display user’s groups in Kali linux?
id userName
For example:
In order to veiw group of users xyz we can user the above command like.
id xyz
Displaying user’s supplementary groups
groups userName
usermod command is used to making changes in existing groups.
How to switch to root user?
sudo su
or
sudo -i
How to add user to sudo group in Kali Linux?
usermod -a -G sudo UserName
for Example:
In order to add xyz user to sudo group we can type the above command as:
usermod -a -G sudo xyz
Changing shell for user in Kali Linux?
chsh -s /bin/bash username
chsh means change shell
-s name fo the shell
/bin/bash
very very informative. thank you soo much
Thanks