Short version
Can I just edit the /etc/hosts file, meaning can I login as user@<hostname I wish to change> without unintentionally breaking something? Would this be enough or is there something else to do?
Long version
I'm trying to create an Ubuntu 16 guest OS in VirtualBox on a Windows 10 host. I have downloaded the Ubuntu 16 .vdi from oxboxes.org, but I don't like the fact that I have to login as osboxes@osboxes. Ultimately I want to login as ab@ab.
First I changed the user name using usermod as described here in @ValentinUveges answer. This worked and so I can now at least login as ab@osboxes. To change @osboxes to @ab I have tried groupmod -n ab osboxes, but this failed.
But at least I think what I really need to change is the /etc/hosts file, which currently contains
cat /etc/hosts
127.0.0.1 localhost
127.0.1.1 osboxes
So can I just edit /etc/hosts and change osboxes to ab in order to allow me to login as ab@ab without unintentionally breaking some parts of the OS? Would this be enough or is there something else to do?
Apart from the steps I mentioned before, this is a "fresh" osboxes.vdi virtual operating system file.