Or HaChaim on Genesis 42:6/אור החיים על בראשית מ״ב:ו׳

1 הוא השליט על הארץ הוא המשביר לכל עם הארץ, he was the ruler of the land; he was the one who sold to all the people of the land. Even though Joseph was the ruler, and it is not usual for the ruler to personally conduct the grain sales, especially when this involved so much effort, he did so himself in order to encounter his brothers eventually.