random man page
random — random lines from a file or random numbers
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:
If the -e option is specified, random does not read or write anything, and simply exits with a random exit value of 0 to denominator-1, inclusive.
The -r option guarantees that the output is unbuffered.