How do I add a user account with admin (sudo) access on Ubuntu or CentOS Linux cloud server? How can I add a new user with admin account level access in Linux?

On the Linux operating system, one needs to use the sudo command to provide admin-level access. In other words, the sudo command grants admin privileges to ordinary users. This page shows how to create a new user with admin (sudo) access on both Ubuntu/Debian and CentOS/RHEL servers. Please note that the following commands will update /etc/passwd, /etc/group, and /etc/shadow files.

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Create a new user account with admin (sudo) access on Ubuntu or Debian Linux

Commands to add or create a sudo user (admin) on an Ubuntu or Debian Linux server:

• Open the terminal application
• For remote Ubuntu/Debian server use the ssh command and log in as the root user using either su or sudo.
• Create a new user named marlena, run: adduser marlena
• Make marlena user ‘sudo user’ (admin) run: usermod -aG sudo marlena
• Verify it by running the id marlena command
• Log in as marlena: su - marlena. Than run sudo command for verification. For example: sudo ls -l /etc/shadow

A note about granting sudo account for an existing Ubuntu/Debian Linux user

The syntax is (must run as the root user):
# adduser {UserNameHere} sudo
## add user named 'sai' to sudo group ##
# adduser sai sudo
Another syntax:
usermod -aG sudo UserNameHere
Log in as the root user and add an existing user accout named ‘sai’ to sudo group:
usermod -aG sudo sai
id sai
See “How to create a new sudo user on Ubuntu Linux server” for more info.

RHEL or CentOS create a new user account with admin (sudo) access

Procedure to add or create a sudo user (admin) on CentOS or RHEL:

• Open the terminal application
• For remote CentOS server use the ssh command and log in as the root user using either su or sudo.
• Create a new CentOS user named vivek, run: useradd vivek
• Set the password, execute: passwd vivek
• Make vivek user ‘sudo user’ on CentOS/RHEL, run : usermod -aG wheel vivek
• Verify it by running the id vivek command

How to grant sudo access for an existing RHEL/CentOS Linux user

The syntax is as follows for the usermod command and id command:
# usermod -aG wheel User-Name-Here
Add an existing user account named kirsh to wheel group. In other words, type the following two commands:
# usermod -aG wheel krish
# id krish
See Add / Create a Sudo User on CentOS Linux 8 for more info.

Conclusion

You learned how to create a sudo (admin level access) user account on both Ubuntu/Debian and RHEL/CentOS Linux servers. See sudo docs here.