Section 12. If the court determines the petitioner entitled to partition, it shall thereupon appoint one or more disinterested commissioners and issue a warrant to them to make partition. The commissioners, before entering upon their duties, shall be sworn to execute the warrant faithfully and impartially, and a certificate of the oath shall be made on the warrant by the person administering it. They shall give at least seven days' notice of the time and place appointed for making the partition, either personally or by registered mail, to all known persons interested therein, and shall make and sign a report of their doings and return it with their warrant.