Getting a text file rid of all superfluous blank lines

[Amadeus W. M.]

On Wed, 30 Nov 2005 11:00:33 +0000, Paul Smith wrote:

> Dear All
> 
> Taking a text file, how can one eliminate at once all superfluous blank lines?
> 
> Thanks in advance,
> 
> Paul

grep . filename

or

cat filename | sed '/^[ \t]*$/d'