If you want to create a new user in a terminal client you can easily do so with the useradd command. To use useradd you will need to be a root user (which is a result of typing su root OR sudo su inside a terminal).
useradd -m -p “” -g users -G “disk,audio,video,floppy,log,network,rfkill,scanner,storage,optical,power,wheel” -s /usr/bin/zsh tester
The above commands will create a user named as tester
Note: you should stay away from the group called adm. Adm is a group, which enables sudo access without a password. The previous might not be desired -if security is a top priority.
When you have created the user, as outlined above, you will next need to set a password for the newly created account:
After you have written the command above a new user account should exist in your Linux system and the password should be enabled.
Additional notes: If you are running Ubuntu/Debian the group wheel is likely replaced with a group sudo. In practice the mean pretty much the same.
Adding stuff to /etc/sudoers.d folder
You can create special permissions for groups and users. One way to do so is to populate sudoers.d folder with appropriate files.
Sometime ago I had a file named as g_includes in /etc/sudoers.d and it contained:
%wheel ALL=(ALL) ALL #Gives sudo access for users in the whell group
#Commands to execute without password for users in the wheel group. Install pm-utils
%wheel ALL= NOPASSWD: /usr/sbin/pm-hibernate #Gives ability to hibernate computer
%wheel ALL= NOPASSWD: /usr/sbin/pm-suspend #Gives ability to suspend computer
%wheel ALL= NOPASSWD: /usr/sbin/shudown #Reboot and shudown commands
For shutdown you can type: shutdown -p
For reboot you can type: shutdown -r
See man shutdown pages for more information. Type: man shutdown when you are in a terminal client. Do note that shutdown commands as listed above will instantly shutdown your computer – so be cautious when using them.