Install the “sudo” Command
You need to run this command as root user:
user@debian:~$ su - Password: root@debian:~ # apt-get install sudo
Create a new user account.
#/usr/sbin/adduser admin
Add the user to the sudo group; By default on Debian systems, members of the group sudo are granted with sudo access. To add a user to the sudo group use the usermod command:
#usermod -aG sudo admin
Check the sudo access
#id admin uid=1001(admin) gid=1001(admin) groups=1001(admin),27(sudo)
The user admin a member of sudo group now and to work as a root, every command must start with sudo (sudo reboot, sudo vim, sudo del, sudo mkdir, sudo……)
Error and solutions
admin@debian9:~$ sudo ifconfig sudo: unable to resolve host (none)
Solutions
Insert hostname to /etc/hostname and /etc/hosts something like:
127.0.0.1 localhost.localdomain localhost 127.0.1.1 debian9