今天安装varnish：
To use the varnish-cache.org repository, add one of
deb http://repo.varnish-cache.org/ubuntu/ hardy varnish-2.1 deb http://repo.varnish-cache.org/ubuntu/ lucid varnish-2.1
to /etc/apt/sources.list, then run apt-get update ; apt-get install varnish.
添加源之后 sudo apt-get update出错：
W: GPG error: http://repo.varnish-cache.org lucid Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 60E7C096C4DEFFEB
sudo gpg --keyserver wwwkeys.eu.pgp.net --recv-keys 60E7C096C4DEFFEB
gpg --armor --export 60E7C096C4DEFFEB | apt-key add -
sudo apt-get update