(1) when installing or updating the software by Yum, you maybe come across the unexpected exit from the Yum tools and then report some errors which indicate some incorrect Yum sources! It maybe result from some obsolete Yum sources,so you'd better delete these problematic sources from /etc/yum.conf or /etc/yum.repos.d/ .
(2)pub－key,some Yum sources need to authorize and you should find pub－key which belongs to the source and import the pub-key: rpm －－import pub－key
The article is worth reading,please refer to
People who spout off one-size-fits-all rules presume to make your design decisions without knowing your requirements. They don't know where you're going but know how you should get there.
Don't trust an answer from someone who doesn't know the question.
摘要: Understand decorator design pattern 阅读全文
摘要: How to limit instantialization?