User administration in Linux

Hi All,

Hope you all are doing good.

In this article, we will know about user administration in Linux.

As we all know that Linux is multi user operating system, means multiple users can access system resources like CPU, memory, RAM ... ,etc application programs at same time. But they have to use different terminals to operate.

Points to keep in mind:

1. A user is any person who uses computer.
2. The system has a name for each account/user it creates, by using that name user will gain access.
3. A user or account of a system is uniquely identified by a numeric number called "UID".
4. There are some reserved words which may not be used as user names. One example is "root"

User Accounts

• One user can create multiple users/accounts in Linux.
• Each user can different privileges.
• The user is having highest authority can restrict the other user to add new users or the data he access to.
• As a default, one account named "root" has access to all the files and to perform any action.

Where User information is stored?
/etc/passwd: Stores the user account information for the system.

command : cat /etc/passwd

/etc/shadow: Stores the password for the various accounts. Only root user have privileges to access these.
command: cat /etc/shadow

/etc/group: Contains your system groups.
command: cat /etc/group

Super user:

1. Super user commonly known as "Root"
2. It is created by default and has User ID and Group ID as 0.
3. It doesn't have password by default, one can assign it by using command sudo passwd root

Swith to super user:
To know about this, please go through https://itamaze.blogspot.com/2020/02/command-to-get-into-root-user-in-linux.html

Sudo - Super user do:

• Adding sudo runs the command with the user privileges.
• Permissions for sudo access is stored in /etc/sudoers
• By default, newly added users don't have sudo permissions.

As part of user administration, we can do following things and many more.
Add, delete user
Assign sudo permissions to user
Create group and add users to it
Remove groups and delete users before before removing group.
Changing permissions(chmod command) for files and directories.
Changing ownership(chown command)

Thanks for reading this article!!