changing system / host name

to change system name or host-name you just can simple enter this command :

sudo hostnamectl set-hostname <my_new_hostname>

example :

sudo systemctl set-hostname boyshostname

sudo error after changing host-name

error after changing the hostname :

$ sudo su -
> sudo : unabe to resolve host boyshostname: name or service not known

Two things to check . /etc/hostname and /etc/hosts they should have the same name for your system .

/etc/hostname file contains just the machine name . /etc/hosts has an entry for localhost . It should have something like

127.0.0.1    localhost
127.0.0.1    my-machine