This is a short and sweet howto that is nonetheless very important. It
is based on my experiences when changing the hostname of a system. The
hostname is effectively just the name of the system. You do not
usually need to change it, but if you do have to for whatever reason,
it isn't very difficult at all.
Whilst changing the hostname is not a difficult task in itself, it can
be dangerous because if the system cannot resolve it's own hostname,
it is impossible to sudo. Thus, if done improperly, changing a
hostname can lock you out of your own system. Firstly, and most
importantly, we make backups. Go to accessories/terminal and paste
this command in, then press enter:
sudo cp /etc/hosts /etc/hosts.bak && sudo cp /etc/hostname /etc/hostname.bak
You MUST make backups, just in case. If you can't boot to a usable
system after finishing this howto, or sudo doesn't work, see the
instructions at the end of this guide. If you aren't completely
familiar with the linux terminal, it might be a good idea to write
these down or print them off.
Ok, now we have made backups, we can edit /etc/hosts:
sudo nano /etc/hosts
You should see what you are looking for fairly quickly, at the top of
the file it should look something like: Code:
Change old_hostname to a new hostname of your choice. Now save and
Second file to edit is /etc/hostname. This does what it says on the
tin, the file will have one line in it and that line is your hostname.
Change it to your new hostname, save and exit.
Now reboot, you should have a perfectly working system in which sudo
works. You can test both sudo and your new hostname by doing, simply:
NOTE: This command does not usually need to be run sudo, we are just
testing both the changed hostname AND sudo at the same time.
If it doesn't work, see below. You DID take backups, didn't you?
- Get into the grub menu by pressing esc on bootup, or allowing it to display automatically if you have set it up like this
- Choose recovery mode
- If prompted, select "drop to single user mode" or similar (note: this applies only on hardy I think)
When you are at a root shell, type the following command:
cp /etc/hosts.bak /etc/hosts && cp /etc/hostname.bak /etc/hostname
Then press ctrl-alt-del and you should reboot back to a perfectly working system.