grep regular expressions

http://www.cyberciti.biz/faq/grep-regular-expressions/

http://droptips.com/using-grep-and-ignoring-case-case-insensitive-grep

	Hello
	hello
	HELLO
	HeLLo
	Ya Hello
	H e l l o
	Y a H e l l o

view raw grepHello.txt hosted with ❤ by GitHub

test code
https://gist.github.com/clementyan/1d7487f75b70739e9cb6953bd09be7c4