GNU bug report logs - #79407
to-file option not working any more?

Previous Next

To reply to this bug, email your comments to 79407 AT debbugs.gnu.org.

Toggle the display of automated, internal messages from the tracker.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Mandar Mitra <mandar.mitra <at> gmail.com>
To: bug-diffutils <at> gnu.org
Subject: to-file option not working any more?
Date: Mon, 8 Sep 2025 14:14:08 +0530

When I specify a directory with the --to-file option, and ask diff to compare multiple files with the corresponding files under the to-file directory, only the first file is diffed; a "No such file or directory" message is displayed for everything else.

Example:

$ /bin/diff -s --to-file=tmp/ 012018.pdf ben.pdf 
Files 012018.pdf and tmp/012018.pdf are identical
/bin/diff: tmp/: No such file or directory

But running diff separately on the two files works:

$ /bin/diff -s --to-file=tmp/ 012018.pdf 
Files 012018.pdf and tmp/012018.pdf are identical

$ /bin/diff -s --to-file=tmp/ ben.pdf 
Files ben.pdf and tmp/ben.pdf are identical

I'm reasonably sure this used to work earlier as I expected, but a quick search did not find any related discussions / bug reports.

Could someone kindly confirm whether this is a bug or incorrect understanding on my part?

Many thanks,
Mandar.

Message #8 received at 79407 <at> debbugs.gnu.org (full text, mbox):

From: Robert Webb <ro.webbdg <at> gmail.com>
Cc: 79407 <at> debbugs.gnu.org
Subject: Re: [bug-diffutils] bug#79407: to-file option not working any more?
Date: Mon, 8 Sep 2025 21:06:11 -0700

[Message part 1 (text/plain, inline)]

On Mon, Sep 8, 2025 at 6:12 AM Mandar Mitra <mandar.mitra <at> gmail.com> wrote:
>
> When I specify a directory with the --to-file option, and ask diff to compare multiple files with the corresponding files under the to-file directory, only the first file is diffed; a "No such file or directory" message is displayed for everything else.
>
> [...]
> I'm reasonably sure this used to work earlier as I expected, but a quick search did not find any related discussions / bug reports.
> Could someone kindly confirm whether this is a bug or incorrect understanding on my part?

Mandar, I can confirm that the --to-file option as a directory results
in only the first command-line file
being diffed, with errors for the others.

This script (also attached as 'runtest02.sh') shows it whether the
first file is identical (b) or different (c):

  DIFFOPTS='-s'
  diff --version

  ecmd() { printf '\n=== %s\n' "$*"  ;"$@" ;}

  setup() {
  test ! -d t  || rm -r t  && mkdir t  || exit
  # Create 3 directories of 3 one-line files
  cd t  && mkdir a b c  || exit
  split --numeric-suffixes=1 -a 1 -l 1 --verbose -- - a/  <<'END'
  x
  xx
  xxx
  END
  split --numeric-suffixes=1 -a 1 -l 1 --verbose -- - b/  <<'END'
  x
  !!
  xxx
  END
  split --numeric-suffixes=1 -a 1 -l 1 --verbose -- - c/  <<'END'
  !
  xx
  !!!
  END
  }

  setup
  ecmd diff ${DIFFOPTS} --to-file b -- a/3 a/2 a/1
  ecmd diff ${DIFFOPTS} --to-file c -- a/3 a/2 a/1

And I just found out that an older version of diff handles this without errors.
First the old one:

  $ runtest02.sh -s
  diff (GNU diffutils) 3.6
  Packaged by openSUSE
  Copyright (C) 2017 Free Software Foundation, Inc.
  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.

  Written by Paul Eggert, Mike Haertel, David Hayes,
  Richard Stallman, and Len Tower.
  creating file 'a/1'
  creating file 'a/2'
  creating file 'a/3'
  creating file 'b/1'
  creating file 'b/2'
  creating file 'b/3'
  creating file 'c/1'
  creating file 'c/2'
  creating file 'c/3'

  === diff -s --to-file b -- a/3 a/2 a/1
  Files a/3 and b/3 are identical
  1c1
  < xx
  ---
  > !!
  Files a/1 and b/1 are identical

  === diff -s --to-file c -- a/3 a/2 a/1
  1c1
  < xxx
  ---
  > !!!
  Files a/2 and c/2 are identical
  1c1
  < x
  ---
  > !

And the new one:

  $ runtest02.sh -s
  diff (GNU diffutils) 3.12
  Packaged by openSUSE
  Copyright (C) 2025 Free Software Foundation, Inc.
  License GPLv3+: GNU GPL version 3 or later
<https://gnu.org/licenses/gpl.html>.
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.

  Written by Paul Eggert, Mike Haertel, David Hayes,
  Richard Stallman, and Len Tower.
  creating file 'a/1'
  creating file 'a/2'
  creating file 'a/3'
  creating file 'b/1'
  creating file 'b/2'
  creating file 'b/3'
  creating file 'c/1'
  creating file 'c/2'
  creating file 'c/3'

  === diff -s --to-file b -- a/3 a/2 a/1
  Files a/3 and b/3 are identical
  diff: b: No such file or directory
  diff: b: No such file or directory

  === diff -s --to-file c -- a/3 a/2 a/1
  1c1
  < xxx
  ---
  > !!!
  diff: c: No such file or directory
  diff: c: No such file or directory

-- 
Robert Webb

[runtest02.sh (application/x-shellscript, attachment)]

Message #11 received at 79407 <at> debbugs.gnu.org (full text, mbox):

From: Mandar Mitra <mandar.mitra <at> gmail.com>
To: Robert Webb <ro.webbdg <at> gmail.com>
Cc: 79407 <at> debbugs.gnu.org
Subject: Re: [bug-diffutils] bug#79407: bug#79407: to-file option not working
 any more?
Date: Tue, 9 Sep 2025 12:18:38 +0530

Robert Webb wrote (Mon, Sep 08, 2025 at 09:06:11PM -0700):
> Mandar, I can confirm that the --to-file option as a directory results
> in only the first command-line file
> being diffed, with errors for the others.

Many thanks for confirming! Is there anything I can do to help fix this, or would it be absolutely straightforward for you to patch the correct handling from 3.6 (say) into 3.12?

Warm regards,
Mandar.

Message #14 received at 79407 <at> debbugs.gnu.org (full text, mbox):

From: Robert Webb <ro.webbdg <at> gmail.com>
Cc: 79407 <at> debbugs.gnu.org
Subject: Re: [bug-diffutils] bug#79407: bug#79407: to-file option not working
 any more?
Date: Tue, 9 Sep 2025 02:11:31 -0700

On Mon, Sep 8, 2025 at 11:48 PM Mandar Mitra <mandar.mitra <at> gmail.com> wrote:
>
> Robert Webb wrote (Mon, Sep 08, 2025 at 09:06:11PM -0700):
> > Mandar, I can confirm that the --to-file option as a directory results
> > in only the first command-line file
> > being diffed, with errors for the others.
>
> Many thanks for confirming! Is there anything I can do to help fix this, or would it be absolutely straightforward for you to patch the correct handling from 3.6 (say) into 3.12?

I am just a user of diffutils, like you.  You could maybe find the
exact version that changed diff's behavior.
That would focus on a small set of source code changes where the
problem might be.
-- 
Robert Webb

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.