Regex syntax

This article is currently a stub; it means I'm aware it's short and I probably intend to expand on the subject in the future!

I can never remember which programs use which regex variants, so here's a quick recap sheet.

	grep (GNU)	sed (GNU)	vim	less (GNU)	python
capture	\( ... \)	\( ... \)	\( ... \)	( ... )	( ... )
option	\|	\|	\|	|	|
word boundary	\< or \>	\< or \>	\< or \>	\< or \>	\b
zero or one	\?	\?	\?	?	?
zero or more	*	*	*	*	*
zero or more (non-greedy)			\{-}	(unknown)	*?
one or more	\+	\+	\+	+	+
one or more (non-greedy)			\{-1,}	(unknown)	+?

References

• https://www.gnu.org/software/grep/manual/html_node/Regular-Expressions.html
• http://vimregex.com/
• https://docs.python.org/3/library/re.html