dontdiff has unfixable problems

From: David Mansfield (
Date: Thu Aug 24 2000 - 13:15:11 EST


I just wanted you to know (and the list to know) that the dontdiff has
some unfixable problems having to do with the following limitation of
diff (from the manpage):

       -X file
              When comparing directories, ignore files and subdi­
              rectories whose basenames match any pattern con­
              tained in file.

The problem is that it only compares *basenames*, and in the kernel
source, we have two files with the same basename but in different
directories, one of which needs to be ignored, the other needs to be

For example, the one I sent you: net/khttpd/times.h should be ignored
but include/linux/times.h should not be. There are 3 versions of
'version.h', the include/linux/version.h which should be ignored, and
include/pcmcia/version.h and arch/i386/math-emu/version.h which should
not be ignored.

The same applies to directory names themselves. We want to ignore
scripts/lxdialog/lxdialog (the executable) but not ignore
scripts/lxdialog (the entire directory!).

I just thought I'd mention this in case you want to put these caveats
into the dontdiff file, or something, or in case anyone out there (like
me) is using these as a basis for setting up CVS.

(Of course in CVS, you can do per-directory ignores which fixes the
problem at the expense of some extra maintenence.)

In case I sound unthankful, however, that is untrue. The dontdiff file
saved me enormous time. I used to have to do 'make distclean' before
doing anything to make sure all the derived files were gone. What a
hassle you have saved me.

David Mansfield
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