Comment 0 for bug 1664438

probably a "paper cut" issue here. On 16.04.

Changed the hostname of a system recently by opening the system settings tool, into details, and typing a new device name.

Noticed afterwards that running sudo commands in the terminal resulted in an 'unable to resolve hostname' message, although the commands ran successfully.

Checked and it looked like changing the name updates /etc/hostname as expected, but it didn't update /etc/hosts for me - it still had:

127.0.0.1 localhost
127.0.1.1 (old hostname)

Replacing the old hostname with the new one removed the message from the terminal when running sudo commands.