From: Christian von Kleist <cvonkleist@...>
Date: 2007-12-06T02:53:18+09:00
Subject: Re: Ruby equivalent for `du`

On Dec 5, 2007 12:10 PM, MonkeeSage <MonkeeSage@gmail.com> wrote:
>
> On Dec 5, 10:51 am, Christian von Kleist <cvonkle...@gmail.com> wrote:
> > I wrote a simple method for recursively finding the size of a
> > directory, because I didn't see anything in File::Stat or FileUtils
> > that does that.  Am I missing it?  Does Ruby already have an
> > equivalent to `du`?
> >
> >   def size(f)
> >     return File.size(f) unless File.directory?(f)
> >     Dir.entries(f)[2..-1].inject(0) {|total, s| total + size(File.join(f, s))}
> >   end
>
> Couple problems with that approach 1.) assuming that ".", ".." are the
> first elements of the entries array, 2.) for deep directories you'll
> run out of stack very quickly. Have a look at the example at the top
> of the Find module. ;)
>
> [1] http://www.ruby-doc.org/core/classes/Find.html
>
> Regards,
> Jordan
>
>


Good point!  Something like %w(. ..).include?(file) would be better
than relying on . and .. to be the first two entries.  I'm not worried
about stack space, though I did consider it.  For this application I
won't find thousands of levels of subdirectories, and even then I
probably wouldn't run out of stack space.  I could rewrite the
recursion as a loop, but...

As you suggested, I should have used Find.find instead.  The
implementation is simpler, more readable, and more robust:

require 'find'
def size(f)
  total = 0
  Find.find(f) {|s| total += File.directory?(s) ? 0 : File.size(s)}
  total
end

(For my application I don't care about the size of directories since
those are highly configuration dependent and this script must produce
the same result with the same file/directory tree on different
computers.)

Thanks, Jordan!