Regular Expressions 101

(?m)applies the following effective flags to the remainder of the pattern: gm

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

^start of line

.+any character (except for line terminators), repeated at least once

Non-Capturing Group(?:\n(?!\n).*|(?<=:)\n{2,}.*)*

*repeats the group contents below any number of times:

1st Alternative\n(?!\n).*

\na line-feed (newline) character (ASCII 10)

Negative Lookahead(?!\n)

\na line-feed (newline) character (ASCII 10)

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

2nd Alternative(?<=:)\n{2,}.*

Positive Lookbehind(?<=:)

:the literal : (58₁₀ / 72₈ / 3A₁₆)

\n{2,}a line-feed (newline) character (ASCII 10), repeated at least 2 times

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

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(?m)^.+(?:\n(?!\n).*|(?<=:)\n{2,}.*)*

Test String
New

ART. WEFWEFEW
  1 SDVSDRG:
     a. wevvdfvdfd
     b. sdfsdfsdfsdfsdfsdghtrhrth


ART. WEFWEFEW
   1 SDVSDRG:

     a. wevvdfvdfd
     b. sdfsdfsdfsdfsdfsdghtrhrth

Regular Expression

Test StringNew

SubstitutionProcessing...

Test String
New

Substitution
Processing...