From: Kendall Gifford <zettabyte@...>
Date: 2010-04-08T05:19:00+09:00
Subject: Re: Copying all Files with New Name

>
> Problem: I actually want to copy the contents of all files that is in a
> particular directory into a new directory.The new files should be of a
> specific size (2MB)and each with a new name (randomly assigned).
>
> My Current Code looks,
>
> require 'ftools'

I recommend using 'fileutils' instead. From the ftools docs:
"FileUtils contains all or nearly all the same functionality and more,
and is a recommended option over ftools"

> testdir = "K:/test"
> # Iterating over each entry
> Dir.entries(testdir).each do |file|

Okay within this context you'll probably need to "filter out" or
ignore the "." and ".." entries. They show up in windows too.

Dir.entries(testdir).reject { |d| %w{. ..}.include?(d) }.each do
|file| # example removes . and ..


> # Joining the path where the files are
>
>   path = File.join testdir, file
>   if File.file? path
>
>          File.open path

You don't need to "open" the file to copy it, whether you're using
ftools *or* fileutils. I'd nuke the "File.open path" line.

>          File.copy(file,'K:/t1') # ...

This is likely failing when you're trying to copy directory entries
"." and ".." which expanded would look like:

File.copy('K:/test/.', 'K:/t1')

However, if you filter out these entries beforehand then this should
work. Also note that it *will* create 'K:/t1' if it doesn't exist and
will also overwrite it if it does (unless there is a
permissions/access issue). The fileutils equivalent would be:

FileUtils.cp(file, 'K:/t1')

>      end
>    end
>  end

Is it just me? I think I cound 1-too-many "ends" there.

>
> When simply trying to copy using File.copy(to,from) it gives following
> error message "No such file or directory K:/"
>

Again, I suspect this is because of the "." or ".." entry being
"copied". File.copy only allows the source to be a file, not a
directory (or so it appears).

>
> Do you think this approach is completely wrong and I should try
> creating File.new and reading every single line and copying over?

No need to use File.new. File.copy or FileUtils.cp do this for you just fine.

>
> Any suggestions about giving random names for the new files..?
>

If you're not worried about race conditions here is a simple version
from one of my old projects.

def unique_filename(location, basename = '', extension = nil, digits = 4)
  extension = extension ? ".#{extension}" : ''
  index = 0
  namer = lambda { "#{basename}#{index.to_s.rjust(digits, '0')}#{extension}" }
  name = namer.call
  while File.exists?(File.join(location, name))
    index += 1
    name = namer.call
  end
  File.join(location, name)
end

#
# Example Usage:
#
require 'fileutils'
source = "K:/test"
dest = "K:"
Dir.entries(source).reject { |d| %w{. ..}.include?(d) }.each do |file|
  FileUtils.cp(File.join(source, file), unique_filename(dest))
end

-- 
Kendall Gifford
zettabyte@gmail.com