最近在执行apt-get update时总有如下错误提示：
W: GPG error: http://debian.cn99.com/debian/ stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F1D53D8C4F368D5D NO_PUBKEY 010908312D230C5F W: You may want to run apt-get update to correct these problems
经过查找资料，总结如下：
$ gpg --keyserver wwwkeys.eu.pgp.net --recv-keys F1D53D8C4F368D5D
$ gpg --armor --export F1D53D8C4F368D5D | apt-key add -
$ gpg --keyserver wwwkeys.eu.pgp.net --recv-keys 010908312D230C5F
$ gpg --armor --export 010908312D230C5F | apt-key add - $ apt-get update
