From: ara.t.howard@...
Date: 2006-03-19T13:49:51+09:00
Subject: Re: safe way to calc md5 on very large files

On Sun, 19 Mar 2006, Stephen Waits wrote:

> rtilley wrote:
>> I'm calculating md5 checksums on very large files (2 GB). This is a safe 
>> way to do so, right? Also... is the file closed when the block exits? I'm 
>> using 'rb' as this is used on Windows and Linux computers.
>> 
>> md5 = Digest::MD5.new()
>> File.open(file, 'rb').each {|line| md5.update(line)}
>> 
>
> Close.. try this..
>
>    require 'md5'
>    File.open(filename,'rb') { |f| MD5.hexdigest(f.read) }
>
> And yes, the file is closed with the block form of open.
>
> --Steve

i think the OP has the right approach - note that an 'f.read' will consume
2GB.  but the OP's code

   harp:~ > cat a.rb
   require 'digest/md5'
   md5 = Digest::MD5.new() and open(ARGV.shift, 'rb').each{|line| md5 << line}
   p md5.hexdigest

will not.

regards.

-a
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