Inserting Blank Line into File (sed/awk/?)

[Ed Allen]

Now for the 'sed' solution....

sed -n -e '{N;N;p;a\

}' filename

Should work from 'sh', 'csh' is more particular about multi-line
arguments.
--
Never trust a man who wears white shoes.           | Ed Allen
Vote Libertarian...     Scare the Hell out of 'em. | Loral Command & Contr. Sys.