For reference, I'm using Mandrake 9.0.

My current understanding is the following:

QT: a software package written in c++ that defines a number of classes and objects to make possible a GUI together with all of the API calls needed to use that GUI.

KDE: a software package that builds on QT and that makes possible an even more powerful GUI. Comes with its own API calls over and above those for QT.

All programs that run under KDE need to hook into KDE by using KDE's and QT's APIs. To do so, when they are compiled, they need to be given what are called QTDIR and KDEDIR environment variables, so that the compiler will be able to properly set up the API calls that need to be in the program's executable file.

This all sounds good in general but it all falls apart when getting into specifics because I have yet to get any source code that I have downloaded to even compile.

First, what specifically and in detail, are QTDIR and KDEDIR? Do I need the source code for QT and KDE and those variables point to whatever subdirectories I put the source code in? Or are simple compiled libraries with header files sufficient? In the case of QT, I was able to find a directory specific to QT that had header files in it but found nothing similar for KDE. Second, where do I set the QTDIR and KDEDIR variables (i.e. in the Linux environment or in the makefile for the program that I want to compile)? I have tried both and have gotten neither to work, possibly because they are pointing to the wrong directories.

Details on the problems that I am having can be found in another Linux Questions thread.

$QTDIR is the directory where the QT libraries and header files have been installed. Depending on how weird your installation is, it should point to somewhere in /usr/lib, maybe even /usr/lib itself. For example, a long time ago my $QTDIR was /usr/lib/qt-2.3.2.

$KDEDIR is the same way; it points to the root of your KDE installation. Again, depending on the weirdness of your system, $KDEDIR can point anywhere. My $KDEDIR is /usr; on other distros, it points somewhere in /opt IIRC.

99% of the time, it doesn't matter, since the autoconf/automake scripts that come with most KDE source programs are able to find these variables easily. If you develop yourself, then it becomes an issue.

dude, i wish i could help you out, but i really don't know. i do have the qt env. varable but not the kde environment variable. but i don't really do much compiling from source if i don't have to either. i think the only kde apps i've compiled from source were some themes and krecord which compiled fine for me. for $QTDIR, though, if you want to know exactly where it's set, provided you can undo the settings you did, you can also in the shell terminal do:

echo $QTDIR

and

echo $KDEDIR.

actually too, you can run a perl script that comes with apache called printenv (printenv.pl for the windows distrobution of apache). that will show you most, if not all, of your environment settings.