1. Every prisoner sentenced to imprisonment and detained in prison shall, subject to the provisions of this Act and subject also to any special order of the court, be employed, trained and treated, whether he is in or is not within the precincts of any prison, in such a manner as the Commissioner may determine, and for that purpose such a prisoner shall, at all times, perform such labour, tasks and other duties as may be assigned to him by the officer-in-charge or any other prison officer in whose charge he may be.