Who is meant by the "Penei ha'Aretz"?
Rashi: The Penei ha'Aretz refers to the rich 1 - who, on account of their higher standard of living, are the most hard-hit in time of famine. 2
Ramban: What the Pasuk means is that Yosef did not open the storehouses until the famine had hit the entire country. 3 Ha'amek Davar - It was not only in the city of Mitzrayim. There were no merchants selling grain!
Gur Aryeh: As the word Penei is extra.
Oznayim la'Torah: Moreover, the poor were initially able to sustain themselves with the grain that had begun to rot - until even that became totally inedible - as the end of the Pasuk indicates.
Ramban: And not from when the people first cried out for bread - since people tend to cry out even when they have a little to eat.
Why does the Torah add, "va'Yechezak ha'Ra'av be'Eretz Mitzrayim"?
Ramban #1: Even after the famine had hit the entire country, he waited a little longer before selling the people grain.
Ramban #2: To teach us the severity of the famine - in that it was a Ra'av Shel Mehumah (where no food is available even in the surrounding areas). 1
Malbim: The grain was finished from the storehouses in the cities. There remained only in the great storehouse in which Yosef stored a fifth of the harvests; so everyone came to Yosef to buy (41:57).
Ha'amek Davar: The grain in the storehouses in the cities lasted only a few days.
See Tif'eres Yisrael to Avos 5:8.
What did Yosef open?
Hadar Zekenim: He opened all the granaries in which there was grain. 1
Ohr ha'Chayim, Malbim: He opened the storehouse in the cities, which stored grain from the surrounding areas. Ha'amek Davar - Yosef's officers sold this.
Gur Aryeh explains Rashi in this way as well. Rashi brings the Targum to show that although the word "Bar" (grain) is not written in the Pasuk, it is implied.
Why did he open all [the storehouses]? He should open only what is needed!
Ohr ha'Chayim #1: He checked which should be sold first, and which can last longer and will not spoil.
Ohr ha'Chayim #2: He stored in every city the grain grown around it. One is more satiated when he has bread in his basket (i.e. everyone should know that the source of grain is nearby). Also, this avoids the toil of bringing from another storehouse [far away]. Also, when the people in the city see how much is stored, their hunger will not be aroused so much. However, the verse teaches that even so, the hunger strengthened due to the severity [of the famine].
When did he open [the storehouses]?
Malbim: It was after the hunger was "Al Kol Penei ha'Aretz;" i.e. individuals had no grain. Also refer to 41:56:2:3.
