shuffle the lines of a large file

[Joerg Schuster]

Hello,

I am looking for a method to "shuffle" the lines of a large file.

I have a corpus of sorted and "uniqed" English sentences that has been
produced with (1):

(1) sort corpus | uniq > corpus.uniq

corpus.uniq is 80G large. The fact that every sentence appears only
once in corpus.uniq plays an important role for the processes
I use to involve my corpus in.  Yet, the alphabetical order is an
unwanted side effect of (1): Very often, I do not want (or rather, I
do not have the computational capacities) to apply a program to all of
corpus.uniq. Yet, any series of lines of corpus.uniq is obviously a
very lopsided set of English sentences.

So, it would be very useful to do one of the following things:

- produce corpus.uniq in a such a way that it is not sorted in any way
- shuffle corpus.uniq > corpus.uniq.shuffled

Unfortunately, none of the machines that I may use has 80G RAM.
So, using a dictionary will not help.

Any ideas?

Joerg Schuster