I have a message saying:"sudo: unable to resolve host (myhostname)" each time i write a command. My hostname do not contain any capital letter or number. thank you
Sometimes, even if you've changed the host name via
raspi-config, the settings don't stick. To make it permanent:
sudo nano /etc/hosts
and change the line that says
assuming that myhostname is the name you want to use. Save, exit and reboot, and the message will go away.