How to fix

An error on sudo: «unable to resolve host»

sudo

As we already saw in “How to set hostname in Linux“, hostname is used to identify the device in network. If we have not hostname matched to our ip, we can’t resolve our host.

Edit /etc/hosts:

127.0.0.1    localhost
# HERE!
127.0.1.1 HOSTNAME
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Or by the one command:

echo 127.0.13.37 $HOSTNAME >> /etc/hosts