Installing only updated headers

[Simon Perkins]

Hi,

I use automake to maintain a collection of common code that I use with a bunch
of other packages. This package includes a number of header files which get
installed in $(pkgincludedir).

Now, whenever I make any change to this package and reinstall, by default every
single header file is reinstalled and the timestamps updated. This means that
any code that depends on any of those headers gets recompiled next time I do a
make, despite the fact that typically most of the headers are unchanged.

The obvious solution is to use the -C option to install which will only copy
header files that have actually changed since the last install. How do I get
automake to do this?

I notice that the Makefiles generated by automake set $(INSTALL) to 'install
-c', and that this -c option is ignored by GNU install. What does the -c option
do? Is it supposed to be -C?

Cheers,

Sy