This program generates random numbers in a user-specified range using the random devices /dev/random and /dev/urandom.
Get a usage message:
rand -h
Generate a random number in the range from 1 to 10 (inclusive):
rand 1 10
Generate a random number from 0 to UINT_MAX:
rand
Generate ten random numbers using /dev/random rather than /dev/urandom:
rand -n 10 -r