The civil service commission in each such county shall promulgate rules and regulations providing for both competitive and medical examinations for the position of correctional officer in each such county subject to the provisions of this article, for appointments to the position of correctional officer and for promotions and for such other matters as are necessary to carry out the purposes of this article. Any such commission shall have the power and authority to require by rules and regulations a physical fitness examination as part of its competitive examination or as a part of its medical examination. Due notice of the contents of all rules and regulations and of any modifications thereof shall be given, by mail, in due season to the appointing officer, and said rules and regulations and any modifications thereof shall also be printed for public distribution. All original appointments on and after the effective date of this article to any position of correctional officer in any county subject to the provisions of this article shall be for a probationary period of one year: Provided, That at any time during the probationary period the probationer may be discharged for just cause in the manner provided in section seventeen of this article. If, at the close of this probationary period, the conduct or capacity of the probationer has not been satisfactory to the appointing sheriff, the probationer shall be notified, in writing, that he will not receive absolute appointment, whereupon his employment shall cease; otherwise, his retention in the position of correctional officer beyond the probationary term shall be equivalent to his absolute appointment.