https://blog.csdn.net/xibeichengf/article/details/51367311
http://www.letuknowit.com/topics/20120329/sample-about-awk-build-in-variable-nr-fnr-nf.html/
https://blog.csdn.net/xibeichengf/article/details/51367311
http://www.letuknowit.com/topics/20120329/sample-about-awk-build-in-variable-nr-fnr-nf.html/