A.T. Robertson Commentary Luke 9:13

"But he said unto them, Give ye them to eat. And they said, We have no more than five loaves and two fishes; except we should go and buy food for all this people." — Luke 9:13 (ASV)

Except we should go and buy food (ε μητ πορευθεντες ημεις αγορασωμεν βρωματα). This is a condition of the third class with the aorist subjunctive (αγορασωμεν), where the conjunction is usually εαν (with negative εαν μη), but not always or necessarily so especially in the Koine. So in 1 Corinthians 14:5 ε μη διερμηνευη and in Php 3:12 ε κα καταλαβω. "Unless" is better here than "except."

Food (βρωματα), means eaten pieces from βιβρωσκω, to eat, somewhat like our "edibles" or vernacular "eats."