use Config::IniFiles;

my $global_ini_data = Config::IniFiles->new( -file => "test.ini" );
my $regex           = $global_ini_data->val( 'client1', 'rename' );
my $filename        = "201306051200foobar.dat";

eval "sub vodoo { \$_[0] =~ $regex }";
vodoo ( $filename ); # this does in-place edit.

print $filename,$/;
__END__
060520.1200foobar.dat