The code you have posted looks nearly the same as PHP. There are a few minor differences, but nothing that you can't look up on php.net.
As for 600 lines being large, maybe. Experiment and try it both ways. See for yourself if there's any performance increase or loss. Maybe you'll want to read in 50 or 100 lines at a time before printing. Try it out.
If you're using a language that requires manual destruction of an object created on the heap that contains the file's contents, then you'll have to manually free the memory. If you're using a garbage collected language, or if your object is created on the stack, then you shouldn't have to worry about it.