Re: How to exclude certain hunk types (added, changed, deleted) from diff

[Matthew Woehlke]

Alexander Kriegisch wrote:
> * Atention, this is not a bug report but a question not answered by the
> manual. If there is an official discussion mailing list for this type of
> inquiry, I beg your pardon and kindly ask you to point me to that list
> or forum. *
>
> I have a special case here in which I am getting huge diff outputs, but
> am interested only in deleted and changed hunks, not added hunks.
> Unfortunately, the latter make up >90% of my diff, resulting in the
> interesting parts being hard to find.
> [snip]
>
> Is there a simple way of telling diff to exclude a/d/c hunks from
> output, but show the remainder in a uni-diff-like fashion? Filtering a
> complete uni-diff with sed or grep is hard, because those tools do not
> have a multi-line regex matching mode which would be needed to do it.
>
> Any ideas?

This should be do-able with sed, something like this:

identify hunk start, print buffer and goto a
:a
examine line
  if desirable hunk, goto b
  if not end of hunk, goto a
delete buffer
goto start
:b
read until end of hunk
print buffer
goto start

...terrible pseudo-code of course, but I've done complex sed like this 
before. Depending on your needs you may need to make (a) print and (b) 
discard.

Ideal? Probably not, but do-able.

--
Matthew
"Passion is inversely proportional to the amount of real information 
available." -- Benford's Law of Controversy
http://en.wikipedia.org/wiki/Benford%27s_law_of_controversy