Resources

• 正则表达式30分钟入门教程
• Regular_expression
• Regexr.com

Different versions

Version	Applications
BRE (POSIX Basic)	grep, sed, awk?, emacs?
ERE (POSIX Extended)	grep -E
Perl regex	grep -P, most of programming languages (Perl, Python, JS, Java, C#)
Vim regex	vim

Syntax differences:

• Perl regex as a de facto standard.
• In BRE/ERE, use [0-9], [ \t] instead of \d, \s.
• In BRE, add backslash before (), {}, |, +.
• No ? in BRE.
• Use :h pattern to check Vim regex.

Quick Ref Card: RegExDiff