converting a list into a line

Hi, this is a pretty intersting problem, I would like to convert a list of words into a concatenated string of words with whitespace between each word.
e.g file list :-
hello
how
are
you
today

convert into
hello how are you today.

What command would I use to do this?

Thanks

here is one trick:

tr "\n" " " < filename #displays on screen

tr "\n" " " < filename >output #redirect to a file

another way to do it :

a=`cat file`
echo $a

greetings...