Change all objects in an Amazon S3 bucket to public-read.

gistfile1.rb

require 'rubygems'
require 'aws-sdk'


# Change this stuff.
AWS.config({
    :access_key_id => 'YOURS_HERE',
    :secret_access_key => 'YOURS_HERE',
})
bucket_name = 'YOUR_BUCKET_NAME'


# If you have millions of objects, run this code on an EC2 instance.
s3 = AWS::S3.new()
bucket = s3.buckets[bucket_name]
bucket.objects.each do |object|
    puts object.key
    object.acl = :public_read
end