That's easy:
echo '127.0.0.1 bitcointalk.org' > /etc/hosts
Or for mortals:
sudo echo '127.0.0.1 bitcointalk.org' > /etc/hosts
Residential smartass here, not being able to resist some smartassery

:
1. Don't overwrite hosts, consider appending (>>)
2. The below would actually work with sudo, otherwise you will get 'permission denied'
sudo sh -c 'echo "127.0.0.1 bitcointalk.org" >> /etc/hosts'
Everybody having lost his hosts file deserves what he gets for just copy-pasting some random command lines from the intertubes..
* psycodad is away trying to restore his elaborate hosts file from backup
