大佬们写的太精髓了，直接传送
sed：
https://www.cnblogs.com/ggjucheng/archive/2013/01/13/2856901.html
https://mp.weixin.qq.com/s/xlQZ5aE7tr3yk-9sHpbabw
grep：
https://www.cnblogs.com/ggjucheng/archive/2013/01/13/2856896.html
https://mp.weixin.qq.com/s/xJsDfuVqv2v3nqda59QN7Q
awk：
https://www.cnblogs.com/ggjucheng/archive/2013/01/13/2858470.html
https://mp.weixin.qq.com/s/4o2raIt1xsNVxGuhh3fXAA