If you ran the following, what would happen?
cat /dev/random > ~/randomFile # don't run
Would it be written until the drive runs out of space, or would the system see a problem with this and stop it (like with an infinite symlink loop)?
It writes until the disk is full (usually there is still some space reserved for the root user). But as the pool of random data is limited, this could take a while.
If you need a certain amount of random data, use
Other possibilities are mentioned in answers to a related question.
However, in almost all cases it is better to use
Installing haveged speeds up