You're right, it doesn't have to be printed line-by-line. But I would recommend it.

The reason is that if the file is large, then the user will (usually) see what's been read and printed so far (assuming no caching, buffering, etc) if you do it line-by-line, but will have to wait until the whole file is processed if you do it as an array slurp. And, possibly, the connection might time-out durring the slurp if you're not careful.

Of course, I could be totally mistaken. :-)

bbfu
Seasons don't fear The Reaper.
Nor do the wind, the sun, and the rain.
We can be like they are.