You can use a negative look-ahead to mimic $
:
[0-9]{6}(\/[0-9]{6})*(?!.)
Using [0-9]
instead of \d
because the latter could have unicode digit chars.
If needed, you can use a negative look-behind to mimic ^
as well:
(?<!.)[0-9]{6}(\/[0-9]{6})*(?!.)