Is it possible to cat only selected lines of a file? For example the first 10, last 15, or "from 20 to 30"?
cat
That's what the head and tail programs are for :)
head
tail
First ten lines
head -n 10 FILE
Last ten lines
tail -n 10 FILE
From lines 3 to 5:
head -n 5 FILE | tail -n 3