How to split file on first empty line in a portable way in shell (e.g. using sed)?

Question

I want to split a file containg HTTP response into two files: one containing only HTTP headers, and one containg the body of a message. For this I need to split a file into

Answer 1

Given the awk script

BEGIN { fout="headers" }
/^$/ { fout="body" }
{ print $0 > fout }

awk -f foo.awk < httpfile will write out the two files headers and body for you.