use strict;
my $str = '|123|;|ABC|;|text
text text|
|124|;|ABB|;|Text
text |
|125|;|BDD|;|text text text|
|126|;|ABC|;|text text
text
text|
|127|;|ABC|;|text text text|';
my $regex = qr/\h*\R\s*([^\s|])/mp;
my $subst = ' $1';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html