Hi thanks for you help. I have version 0.23 for pkg-config When I run the pkg-config --print-errors --cflags xt .... I get: Package xt was not found in the pkg-config search path. Perhaps you should add the directory containing 'xt.pc' to the PKG_CONFIG_PATH environment variable No package 'xt' found. I added the path: export PKG_CONFIG_PATH=/usr/lib/pkgconfig:/usr/local/lib/pkgconfig and still get the same error message. If I run: pkg-config --cflags glib-2.0 I get: -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include I checked /usr/share/aclocal/ for the pkg.m4 file but It is not there. So I reinstalled the pkg-config-0.23. ./configure --prefix=/usr make make install then I: autoreconf the libXt-1.0.8 this thime no warnings were diplayed I ran: ./configure --prefix=/usr make make install now when I run: pkg-config --modversion xt I get: 1.0.8 Thanks for your help. Regards <div class="gmail_quote">On Tue, Aug 24, 2010 at 8:47 AM, Gaetan Nadon <<a href="mailto:memsize@videotron.ca">memsize@videotron.ca</a>> wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <div><div class="im"> On Mon, 2010-08-23 at 17:59 -0500, Pedro Parra wrote: <blockquote type="CITE"> It seems as if the pkgconfig packages is not installed but I believe it is installed, since I can type pkg-config --help and I get the help menu. I can see all the .pc files from different libraries under /usr/lib/pkgconfig </blockquote></div> Perhaps you have an old version or a damaged installation. I have version 0.22 but version 0.18.1 should do. The macros are in /usr/share/aclocal/pkg.m4 on a Debian Linux distro. All X packages would fail they all use those statements. You should be able to display the C flags: <blockquote> <pre>pkg-config --print-errors --cflags xt </pre> </blockquote> See <a href="http://wiki.x.org/wiki/ModularDevelopersGuide#RequiredTools" target="_blank">http://wiki.x.org/wiki/ModularDevelopersGuide#RequiredTools</a> for toolchain requirements. </div> </blockquote></div>