怎么更新LINUX

我用up2date -u -f 提示
Your GPG keyring does not contain the Red Hat, Inc. public key.
Without it, you will be unable to verify that packages Update Agent downloads
are securely signed by Red Hat.

Your Update Agent options specify that you want to use GPG.

To install the key, run the following as root:

    rpm --import /usr/share/rhn/RPM-GPG-KEY
请大哥门帮忙啊
给一个完整容易的方法

[code:1]sudo apt-get update
sudo apt-get dist-upgrade[/code:1]

好的 我回去看看行不行 先在这里谢谢了啊 我建了一个linux群
希望高手们进来指教
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