Here is a little Unix command line trick. I've been looking at the
differences between version releases in software like GDAL, HDF4,
HDF5, etc. There is often a lot of noise (aka non-functional changes)
that get in the way of my trying to understand what is different. The
diff tool is pretty useful and I often look at diffs in emacs and
appreciate the highlighting of Diff mode. However, I'd rather not
have this noise. In the case of GDAL, that is a lot of copyright and
svn Id changes. Those don't change the bevior of the code. Here is
how to get them out using the diff ----ignore-matching-lines (-I) flag.
Just repeat the flag for each thing you want to not get used for diffs.
e.g.
diff -ruN gdal-1.1[01].0/port -I 'Copyright' -I '$Id:' > port.diffThat says to recursively produce "unified" format diffs with the contents of new files shown, but leave out lines with "Copyright" and "$Id:'. The two -I flags drop the diff file from 7500 lines to 6200 lines for the changes between GDAL 1.10.0 and 1.11.0 in the port directory. Every little bit of help makes things easier.
