use strict;
my $str = '{#HEXCOLOR}TEXT TEXT TEXT
{#FF00FF}Hello
{#FF00FF}good one here{/}
{#HEXCOLOR}inline text{#FF00FF}Hello{#FF00FF}test{/}
';
my $regex = qr/({#[^}]+}[^{\r\n]+)(?={#|$)/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