#!/usr/bin/perl

my $s = "blah,blah,blah <PgfTag `Normal \(T\)'> yadda,yadda,yadda";
print "s =\t\"$s\"\n";

#my $pattern = qr{\s*<PgfTag `Normal \(T\)'>\s*};
my $pattern = qr{
    \s*
        <PgfTag `Normal \(T\)'>
    \s*
};

my $k = 0;

$s =~ s/$pattern/++$k && ','/gex;

print "$k change(s)\n";
print "s =\t\"$s\"\n";