Random generators

random-hex.rb

#!/usr/bin/env ruby

require 'securerandom'

print 'Enter desired length of random hex string: '

length = gets

begin
  actual_length = Integer(length)
  byte_length = (actual_length / 2.0).ceil
  raise unless byte_length > 0
rescue
  puts 'Invalid length.'
  exit 1
end

puts SecureRandom.hex(byte_length)[0, actual_length]

random-number.rb

#!/usr/bin/env ruby

require 'securerandom'

print 'Enter desired number of digits: '

digits = gets

begin
  length = Integer(digits)
  raise unless length > 0
rescue
  puts 'Invalid number of digits.'
  exit 1
end

puts format "%0#{length}d", SecureRandom.random_number(10**length)