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D:\>perl -lne "print /^[0-8]{9}$/ && !/(.)(?=.*\1)/ ? 'ok' : 'not ok'" 1234 ... 010101010 not ok ^Z
D:\>perl -lne "print /^(?:([0-8])(?!.*\1)){9}$/ ? 'ok' : 'not ok'" 123456780 ... 123456781 not ok ^Z