I had to remove one line of a 20GB MySQL dump file and was wondering how I could do this.
Actually there are a few ways, but hexdump worked best for me.
aptitude install hexdump
Will get you started on Debian and here is the syntax for editing a file:
hexedit largefile.sql.dump tab (switch to ASCII side) move to the position you want to alter/erase space (repeat as needed until your header is gone) F2 (save)/Ctrl-X (save and exit)/Ctrl-C (exit without saving)