Every executor or administrator shall, immediately after his appointment, publish a notice thereof in some newspaper published in this territory, as may be designated by the court, as often as once a week for four successive weeks, and oftener if the court so directs. The executor or administrator shall also post a notice in at least three public places, to be designated by the court in its order, one of which shall be at or immediately adjacent to the post office nearest the residence of the decedent at the time of his death. Such notice shall require all persons having claims against the estate to present them, with the proper vouchers, within six months from the date of the notice, to the executor or administrator, at a place within this territory therein specified.