Generate SHA256 recursively in a directory tree. Uses the same checksum file format as https://linux.die.net/man/1/sha256sum

recursive-hashes

#!/usr/bin/env ruby

require "digest"
require "find"
require "optparse"

options = {}
OptionParser.new do |opts|
  opts.banner = "Usage: recursive-hashes [options]"

  opts.on("-c", "--check DIR", "Check hashes") do |c|
    options[:check] = c
  end

  opts.on("-g", "--generate DIR", "Generate SHA256SUMS files") do |v|
    options[:generate] = v
  end

  opts.on("-h", "--help", "Prints this help") do
    puts opts
    exit
  end
end.parse!

puts options.inspect

if options[:generate]
  Find.find(options[:generate]) do |path|
    if FileTest.directory?(path)
      if File.basename(path)[0] == "."
        Find.prune
        # Don't look any further into this directory
      else
        files = Dir.glob(File.expand_path("*.*", path)).reject { |f| File.directory?(f) }

        if files.any?
          puts "#{files.size} file(s) in #{path}"

          hashes = files.map do |file|
            sha256 = Digest::SHA256.file(file)
            [sha256.hexdigest, File.basename(file)].join("  ")
          end

          digest_file = File.expand_path("SHA256SUMS", path)
          File.open(digest_file, "w+") do |f|
            f.write hashes.join("\n")
            f.write "\n"
          end

          puts "  -> created SHA256SUMS"
        end

        next
      end
    end
  end
end

#!/bin/bash
shopt -s globstar
sha256sum ./** > ../sums.txt