Ruby SecureRandom fake string of alphanumeric characters; always lead with alphabetic characters.

ruby-securerandom-fake-string-of-alphanumeric-characters-always-lead-with-alphabetic-characters.rb

# 
# "generate a string with 0-9a-z (36 characters) that is ALWAYS 12 characters long. Change 12 to whatever length you want."
# -- Gerry Shaw via https://stackoverflow.com/questions/88311/how-to-generate-a-random-string-in-ruby#comment35392122_1619602
# 
# min length is 6
def fake_code(length = 12)
  # always lead with four chars
  str = SecureRandom.hex.gsub(/\d/, "")[0..3]
  
  # followed by chars or int
  str << SecureRandom.random_number(36**12).to_s(36).rjust(12, "0")[0..(length-5)]
end

secure-random-hex-partition-string-in-half.rb

# SecureRandom.hex.partition(/.{16}\z/)[0..1]
# => ["1e409ee9d1d0c2ca", "03968cd52870b79a"]