Regular Expressions 101

Explanation
Pro

^start of line

sitemap:the literal text sitemap: (case insensitive)

Group 1(.*)

.*any character (except for line terminators), repeated any number of times

$end of line

Global pattern flags

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Detailed match information will be displayed here automatically.

26 tokens

^sitemap:(.*)$

New

# Group 1
User-agent: Googlebot
Disallow: /nogooglebot/

# Group 2
User-agent: *
Allow: /

Sitemap: http://www.example.com/sitemap.xml

# Group 1
User-agent: Googlebot
Disallow: /nogooglebot/

# Group 2
User-agent: *
Allow: /

Sitemap: http://www.example.com/sitemap.xml