deleting some empty lines with sed

[Lou Kates]

In article <1991Apr27.143519.26256 at daimi.aau.dk> datpete at daimi.aau.dk (Peter Andersen) writes:
>If two or more blank lines appear, I want to remove all but
>one of these.

The following  awk script (its called  nawk on my system) will do
this:

		nawk 'NF || !b; {b = !NF}'

b is a  flag which is true  if the previous input line was blank.
The first statement of  the script  prints the current line if it
has fields or  if b is false (or null as it will be on the  first
line of input). The second statement of the script sets b.

Lou Kates, Teleride Sage Ltd., louk%tslwat at watmath.waterloo.edu