From: Robert Klemme <shortcutter@...>
Date: 2011-03-08T18:49:11+09:00
Subject: Re: Checking if two files are the same

On Tue, Mar 8, 2011 at 9:48 AM, Brian Candler <b.candler@pobox.com> wrote:
> New C. wrote in post #985925:
>> I have a got a few folders which may have same files under different
>> names.
>> Is there any way I can find which these files are using ruby ?
>
> Here is a little ruby script I use for finding and/or deleting duplicate
> image and video files downloaded from my camera - it will work for any
> sort of file.
>
> #!/usr/bin/ruby -w
> require 'digest/sha1'
> if ARGV[0] == "-d"
>  do_delete = true
>  ARGV.shift
> end
>
> seen = {}
> dirs = ARGV.empty? ? ["#{ENV["HOME"]}/Pictures"] : ARGV
>
> dirs.each do |dir|
>  Dir["#{dir}/**/*"].sort.each do |fn|
>    next if File.directory?(fn)
>    hash = Digest::SHA1.file(fn).hexdigest
>    if seen[hash]
>      puts "#{fn} is dupe of #{seen[hash]}"
>      if do_delete
>        File.delete(fn)
>        puts "DELETED"
>      end
>    else
>      seen[hash] = fn
>    end
>  end
> end

For this idiom Hash#fetch can be used nicely:

irb(main):008:0> h={};
10.times {|i|
  puts i
  h.fetch(i % 3) {|x| printf "first %p\n", i; h[x]=true; nil} and
    printf "duplicate %p\n", i}
0
first 0
1
first 1
2
first 2
3
duplicate 3
4
duplicate 4
5
duplicate 5
6
duplicate 6
7
duplicate 7
8
duplicate 8
9
duplicate 9
=> 10
irb(main):009:0>

... for arbitrary values of "nice". ;-)

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/