Creates a file filled with random content.

random-file.rb

#!/usr/bin/env ruby

require 'securerandom'

TARGET_FILE_NAME = "random-file.iso"
TARGET_FILE_SIZE = 4707319808 # DVD-RW
CHUNK_SIZE = 1000000 # 1 MB

file = File.new TARGET_FILE_NAME, 'w'

bytes_written = 0
bytes_remaining = TARGET_FILE_SIZE

begin
  chunk_size = if bytes_remaining > CHUNK_SIZE then CHUNK_SIZE else bytes_remaining end
  file << SecureRandom.random_bytes(chunk_size)
  bytes_written += chunk_size
  bytes_remaining -= chunk_size
end until bytes_written == TARGET_FILE_SIZE