In case you have a big file which contains a lot of content (2+ GB). And you only need a small part from the file (the part is continuous string from line X to line Y).
You have many ways to achieve that :
vieditor and delete from line 1 to line (X-1) by press
[X-1]ddthen go to line (Y-X+2) and delete to last line by press
sed -n '[X][Y]p' [input_file] > [output_file]. Example :
sed -n '15,68p' a.sql > b.sql
head -n[Y] [input_file] | tail -n[Y-X+1] > [output_file]
I personally recommend using the
sed way, it's faster and simpler to remember.