Perl Regex To Condense Multiple Line Breaks

Question

I can\'t seem to figure out the right syntax but I want a Perl regular expression to find where there are two or more line breaks in a row and condense them into just 2 line

Answer 1

This does it:

#!/usr/bin/env perl
use strict;
use warnings;
my $string;
{
   local $/=undef;
   $string =;
} 
print "Before:\n$string\n============";

$string=~s/\n{2,}/\n\n/g;
print "After:\n$string\n\nBye Bye!";

__DATA__
Line 1
Line 2






Line 9
Line 10

Line 12



Line 16


Line 19

Output:

Before:
Line 1
Line 2






Line 9
Line 10

Line 12



Line 16


Line 19
============After:
Line 1
Line 2

Line 9
Line 10

Line 12

Line 16

Line 19

Perl also supports the \R character class for platform independence. See this SO link. Your regex would then be s/\R{2,}/\n\n/g;