As some people know, the Linux device for generating random numbers (/dev/random) blocks when there isn’t sufficient entropy to safely generate random numbers. But people will still persist on advising using /dev/urandom as an alternative :-
“To sum up, under both Linux and FreeBSD, you should use /dev/urandom, not /dev/random.”
“Just go ahead and use /dev/urandom as is”
“Oracle wants us to move /dev/random and link /dev/urandom”
“You can remove /dev/random and link that to /dev/urandom to help prevent blocking”
Now it is true that /dev/urandom is usually good enough, but to advise people to use /dev/urandom without considering whether it is sufficient or not is irresponsible. True random numbers can be very important for cryptography, and without knowing it, we use cryptography every day; such as when we browse the web, make ssh connections, check PGP keys, etc. Using a weak random number generator can weaken the cryptographic process fatally.