the system sometimes shows the message “xxx is not in the sudoers file. This incident will be reported” when we use sudo command. XXX is your username
We could use ‘visudo’ command to resolve this issue
visudo /etc/sudoers
you will find there is a line:
root ALL=(ALL) ALL
Please add the a new line below it and then save and exit
XXX ALL=(ALL) ALL
Note: one the root could edit this file, visudo will use VI to edit sudoers file, so we can press ESC and then input :wq to save sudoers and exit VI.
http://www.ibm.com/developerworks/cn/aix/library/au-sudo/?ca=drs-tp4608