The random() function uses a nonlinear additive feedback random number
generator employing a default table of size 31 long integers to return
successive pseudo-random numbers in the range from 0 to RAND_MAX. The
period of this random number generator is very large, approximately
16*((2^31)-1).
The character special files /dev/random and /dev/urandom (present since
Linux 1.3.30) provide an interface to the kernel's random number
generator. File /dev/random has major device number 1 and minor device
number 8. File /dev/urandom has major device number 1 and minor device
number 9.
random reads lines from the standard input and copies them to the
standard output with a probability of 1/denominator. The default value
for denominator is 2.
The options are as follows: