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RE: octal dump



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>---- Original Message ----
>From: girish@hri.res.in
>To: debian-user@lists.debian.org
>Subject: RE: octal dump
>Date: Mon, 17 Nov 2008 22:24:49 +0530
>
>>Hello,
>>
>>I was trying to understand octal dumps today that can be obtained
>>using od.  But two questions cropped up:
>>
>>1. When would an octal dump be useful?  Surely not in perusing text
>>   files?!  And when people say they use octal (or hex) dump to
>check
>>   and edit binary files, how do they learn to do so?
>>
>>2. I understand that od shows the file offsets in decimal if I say
>'od
>>   -Ad'.  But I find that the offset of the last line does not match
>>   with the size of the file given by 'du -h'.  Why is that?
>>
>>I really am puzzled after bumping into this command by chance.  Any
>>comments would help.
>>
>>Thanks,
>>Girish.
>>
>>-- 
>>Girish Kulkarni - Allahabad, India - http://girish.50webs.com
>>

I've never used octal dumps (octal maps three bits into one octal
"digit") but I've used hex a lot (maps four bits into one hex
"digit").  Bit twiddlers are used to reading memory addresses which
may be 32 or 64 bits as hex numbers-saves time and lessens the
probability of a mistake.  After doing it for a while the conversion
to and from hex is done relatively automatically by the brain.
Larry
P.S.  Even us old timers remember also reading machine code dumps in
hex.  I guess I don't go back far enough for octal
>>
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