When you use sudo, you will see the error messages as below.
<em>user-name</em> is not in the sudoers file. This incident will be reported.
The default user does not have the sudo group. Let’s assume that the user name is jaerock. We need to make jaerock have sudo group. To make this change, use usermod command. Only super user can use this command. Thus, switch to super user using su, then you will be asked to enter a password. Use your user password. Then use usermod command to add sudo group to your user account. After this, simply use exit. Then you will be back to your account.
su
usermod -a -G sudo jaerock
exit