Create a file with random content with a given size

On my $DAY_JOB my colleague had been developing a feature which should handle huge files. And in order to test this feature he required such a file. With any content. The only requirement — it has to be couple gigabytes in size. An obvious solution is just to ask others for a such file and send it over the wire. But it was inconvenient at the moment for some reasons and because we are using Linux, I suggested another solution:

mn@notebook:~$ dd if=/dev/urandom of=dvd.iso bs=1 count=1M
1048576+0 records in
1048576+0 records out
1048576 bytes (1.0 MB) copied, 8.38094 s, 125 kB/s
mn@notebook:~$