Re: Bug diff: no difference between 0 byte files and no files.

[J.C. Pizarro]

2007/7/31, Andreas Schwab <address@hidden> wrote:
> "J.C. Pizarro" <address@hidden> writes:
>
> > Hi, diff v2.8.1 and v2.8.7 ignore 0 byte files, and it's a bug.
> >
> > The program diff doesn't see the difference between 0 byte file and no file.
> >
> >   mkdir dir1 dir2 2> /dev/null ; cat /dev/null > dir1/empty.out ; \
> >   tree dir1 dir2 ; echo "Differences between dir1 and dir2 from diff:" ; \
> >   diff -Nduar dir1 dir2 ; rm -f dir1/empty.out ; rmdir dir1 dir2
>
> Not a bug:
>
>   -N  --new-file  Treat absent files as empty.
>
> Andreas.
>
> --
> Andreas Schwab, SuSE Labs, address@hidden
> SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
> PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
> "And now for something completely different."
>

Yes a bug (without -N option):

  mkdir dir1 dir2 2> /dev/null ; cat /dev/null > dir1/empty.out ; \
  tree dir1 dir2 ; echo "Differences between dir1 and dir2 from diff:" ; \
  diff -duar dir1 dir2 | tee dir1_to_dir2.patch ; rm -f dir1/empty.out ; \
  rmdir dir1 dir2

  ls -l dir1_to_dir2.patch ; cat dir1_to_dir2.patch ; \
  mkdir dir1 2> /dev/null ; cat /dev/null > dir1/empty.out ; \
  patch -p0 < dir1_to_dir2.patch ; mv dir1 dir2 ; tree dir2 ; \
  rm -f dir2/empty.out 2> /dev/null ; rmdir dir2 ; rm -f dir1_to_dir2.patch


In the console:

address@hidden:~$
dir1
`-- empty.out
dir2

0 directories, 1 file
Differences between dir1 and dir2 from diff:
Only in dir1: empty.out
address@hidden:~$

address@hidden:~$
-rw-r--r-- 1 jc jc 24 2007-07-31 14:55 dir1_to_dir2.patch
Only in dir1: empty.out
patch: **** Only garbage was found in the patch input.
dir2
`-- empty.out

0 directories, 1 file
address@hidden:~$

The problem will be the same.
The bug of the no-elimination of 0 byte file dir2/empty.out still exists.

Without -N appears "patch: **** Only garbage was found in the patch input."
With -N option doesn't appear this strange previous message.

J.C. sincerely yours :)