Пробую так: ^(\d+|\d+[a-z]|\d+[a-z]\/\d+)$
Работает, но если заменить буквы на кириллицу, то не работает.
Подозреваю, что дело в кодировках
[root@nodeny ~]# locale
LANG=ru_UA.UTF-8
LC_CTYPE="ru_UA.UTF-8"
LC_NUMERIC="ru_UA.UTF-8"
LC_TIME="ru_UA.UTF-8"
LC_COLLATE="ru_UA.UTF-8"
LC_MONETARY="ru_UA.UTF-8"
LC_MESSAGES="ru_UA.UTF-8"
LC_PAPER="ru_UA.UTF-8"
LC_NAME="ru_UA.UTF-8"
LC_ADDRESS="ru_UA.UTF-8"
LC_TELEPHONE="ru_UA.UTF-8"
LC_MEASUREMENT="ru_UA.UTF-8"
LC_IDENTIFICATION="ru_UA.UTF-8"
LC_ALL=