# Keep around:
my $string = "Sat, 05 Jan 2013 04:00:15 GMT";
my $match = substr($string, 5, 11); 
print "Take out and keep: <$match> found in <$string>\n";
# Output: Take out and keep: <05 Jan 2013> found in <Sat, 05 Jan 2013 04:00:15 GMT>