Emacs has an interactive regex mode that shows matches as you type.
To go into the mode, M-x regexp-builder. Type C-c C-q to exit the mode.
Watch out for escape characters. Emacs requires you to escape \, so type \b for \b
Copy the following text into emacs and then M-x regexp-builder
Lots of Grey things 50 shades of Grey Earl Grey Tea Lady Grey Graybeard the pirate Greyhound buses "You're looking grey," he said. "That's the greyest greyhound I ever saw," said Earl Grey. Grey1: Dark Gray Grey35: Mid grey Grey44: Battleship grey Grey100: The colour of TV tuned to a dead channel
In regexp-builder, type…
Grey to find all the Greys Gray to find all the Grays Gr[ae]y to find all the Greys and Grays \\bGray\\b to find Gray on its on and not part of another word ^Gray to find lines beginning with Gray grey$ to find lines ending in grey grey\\(hound\\)? to find all appearances of grey and greyhound grey[0-9] to find all the shades of grey ending with a digit grey[0-9]\\{2\\} to find all the shades of grey with exactly two digits
Follow the link for some Regexp Exercises to try out
Read more about Regexps at the Emacs Wiki
Tony Ballantyne Tech 