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Re: Why not diff binaries?

On 17 Jul 2000, Riku Saikkonen wrote:

> "Pavel M. Penev" <kal_pav@sz.techno-link.com> writes:
> >Can someone tell me a sensible reason for not having a 'diff' equivalent
> >for binary file?
> There is "cmp", but it reports only the position of the first
> differing byte (if any).
> As for why not:
>  * diff is helped a lot by the fact that the input is line-based text.
>    And diff doesn't work very well if the lines are very short or
>    there are lots of small changes inside lines.
>    I don't know if there are algorithms for detecting differences in
>    streams of bytes (instead of lines); probably there are, but I
>    don't know if they work as well as the text comparison algorithm in
>    diff.
>    (There is also wdiff, which works word-wise, and seems to work okay
>    for what it's designed: calculating differences between reformatted
>    paragraphs of text.)
>  * There isn't as much use for binary patches than for textual ones,
>    because binary executables are platform-dependent.
> It should be possible to dump the binary files in a textual format
> with "od" (use one byte or word per line, unless you know the data has
> larger structures that you want to compare as a whole) and run diff on
> those, but I don't know how well that would work.
> -- 
> -=- Rjs -=- rjs@lloke.dna.fi
10X! I think I am going to continue my issues in another mail-list.

Pavel M. Penev

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