From: Rob Biedenharn <Rob@...>
Date: 2009-11-30T06:29:02+09:00
Subject: Re: Ruby byte access to disk sectors like dd does


On Nov 29, 2009, at 8:00 AM, Robert Klemme wrote:

> On 28.11.2009 19:12, Bill Kelly wrote:
>> From: "Robert Klemme" <shortcutter@googlemail.com>
>>> On 11/28/2009 01:26 AM, Bill Kelly wrote:
>>>> :)  Here's a stab at it... (it does work properly if the last
>>>> read returns fewer than 16 bytes.)
>>> What makes it stop working properly if the file size is a multiple  
>>> of 16?
>> It works OK in either case, is what I was trying to say.  :)
>
> Ah, OK.  Thanks for the clarification!
>
>>>> ruby -e 'File.open("/dev/hdb", "rb") {|io| print(io.read(512))}' |
>>>> ruby -e 'i=0; while(x=ARGF.read(16)); puts("%08x %-32s %s" % [i,  
>>>> x.unpack("H*"), x.tr("^\040-\176",".")]); i+=16; end'
>>> Why do you separate this in two processes?  I've munged it a bit...
>> Same reason dd and hexdump are separate programs.
>> http://www.faqs.org/docs/artu/ch01s06.html
>
> Well, but in light of that neither a Ruby replacement of dd or  
> hexdump is needed as they do exist already and do their job properly  
> - and likely even more efficient than Ruby. :-)
>
> <quiz-idea>
> Write a program that reads binary files and outputs them in a  
> similar format as "hexdump -C" integrating features of "dd": The  
> program needs to be able to understand a series of paired options "-- 
> start X --length Y" and "--start X --end Z" (X, Y, Z of course being  
> integer numbers with obvious properties) which denote the regions of  
> the stream to read.  The program must be capable of reading from a  
> pipe as well!  Bonus points for accepting parameter "--block-size B"  
> which determines the size of chunks read in one read operation.  You  
> may also invent any number of additional options which control  
> formatting of the output.  Source code must be shorter than 20 lines  
> of code per additional option. ;-)
> </quiz-idea>
>
> Kind regards
>
> 	robert
>
> -- 
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/

That sounds like quiz #171 - hexdump - from early this year.

http://rubyquiz.strd6.com/quizzes/171

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com