The pharaoh had to feed his people, and, being a god on earth, during some time periods in ancient Egypt, he was seen as being in control of the fertilizing floods of the Nile. This also meant that the pharaoh had basically limitless power to do what he wanted and to have what he wanted. I'm not sure that I would ever want the pressure that must have been on the shoulders of the pharaoh though. Imagine the feeling if the river wasn't doing what it was supposed to do and a famine came.
Of course we must remember that a parent must discipline or protect his or her children too. These were other main duties of the pharaoh. What the pharaoh said was the law of the land in Egypt, and those that broke his law must suffer the consequences. Likewise, he had to do everything in his power to protect Egypt from foreign invasion or threats from within. Again, quite a pressure filled job.
These duties of the pharaoh are illustrated well by the symbols of the pharaoh, the crook and the flail. The crook, like a shepherd's crook, is a symbol of leadership, protection, and the fatherliness of the pharaoh. The flail is a symbol of discipline (as a whip or weapon) and also a symbol of the pharaoh's duty to feed his people (as a farm tool).
(Image: the "original" god/pharaoh Osiris holding crook and flail.) (public domain)