This tutorial is intented for people who are using Debian, and want to check out or test some idea on existing KDE code without much hassle.
This tutorial shows a way of easily downloading and compiling and running the KDE software that is used on your Debian system.
First you need to add the source repositories to your installation. This is normally done by editing /etc/apt/sources.list as user root and adding a line starting with deb-src: <syntaxhighlight lang="bash"> kdesudo kwrite /etc/apt/sources.list
The easy way is to copy your existing deb line onto a new line, and change deb to deb-src:
In most(all?) of the cases this will work.
Then you must let this change know to the package manager, so do as root:
<syntaxhighlight lang="bash">aptitude update
Setting up the dependencies
Now you want to be able to build a certain package, and in this example we will build the kcontrol configuration modules(aka KCM modules) and the application containing them called systemsettings. Let's say we want to see if we can maybe fix some bug in the Display configuration module, which is called randr actually. In debian the package is systemsettings, so first we will get the build dependencies of that package, so do as root:
<syntaxhighlight lang="bash">aptitude build-dep systemsettings
This will download and install all needed dependencies which are some build tools and otherwise mostly packages with -dev at the end of them, which are in most cases a bunch of header files.
Getting the source
As a regular user, create a new directory, and fetch the sources for the package: <syntaxhighlight lang="bash"> mkdir ~/kde4devel cd ~/kde4devel apt-get source systemsettings
This downloads the source and applies all the debian patches for you. In this case, it downloads kdebase-workspace because the systemsettings code is only a small part of the kdebase-workspace package. Now go into the newly extracted directory. This is kdebase-workspace-4.3.2 in my case.
<syntaxhighlight lang="bash"> cd kdebase-workspace-4.3.2
Building the source
Now we go into the source directory, and let cmake generate the Makefiles, which are then used by the make command to build the code. This is done like this:
<syntaxhighlight lang="bash"> cmake . # don't forget the extra space+point!
Later we'll have to install the built files, you probably don't want to do this as root. So it is better to call cmake like this:
<syntaxhighlight lang="bash"> cmake -DCMAKE_INSTALL_PREFIX=$HOME/kde4devel/root .
cmake supports a nice Qt GUI to configure your build process. If you have the package cmake-qt-gui installed, you can replace cmake with cmake-gui. More information on cmake is available in the CMake Tutorial.
With cmake-gui it is easy to select only the components starting with BUILD_ you want. In my case it was rather the components I'm sure of that I didn't want :). So I ended up with only BUILD_kcontrol and systemsettings and didn't touch any of the other settings below. Then click on the Configure button and, if successful, then on the Generate button. Close the program now.
Now we have makefiles that will only build what we chose to build in the cmake-gui program. So now you can execute the make command to start:
<syntaxhighlight lang="bash"> make
Now it is building!
Changing the source
We will now go to the directory of the randr module we want to develop on:
<syntaxhighlight lang="bash"> cd kcontrol/randr
Edit some file, and then rebuild simply by running make again in this directory:
<syntaxhighlight lang="bash"> make
The module is now being rebuilt. Likewise we can change something in a source file in the systemsettings source directory, and rebuild it using make
<syntaxhighlight lang="bash"> cd ~/kde4devel/kdebase-workspace-4.3.2/systemsettings make
To have a full rebuild of the code, first do make clean before the make command.
Running the program
This may be somewhat difficult, but we start easy ;)
You go into the systemsettings/app directory, and there start that self-compiled code like this: <syntaxhighlight lang="bash"> cd ~/kde4devel/kdebase-workspace-4.3.2/systemsettings/app ./systemsettings
This will indeed run your new code. But it is better to first install it into your ~/kde4devel/root directory so everything is setup correctly in a certain hierarchy, because the systemsettings program might need to find or access certain files to function properly. You do this with the simple command make install in the main directory of the application or module you just built:
<syntaxhighlight lang="bash"> cd ~/kde4devel/kdebase-workspace-4.3.2/systemsettings make install cd ~/kde4devel/kdebase-workspace-4.3.2/kcontrol/randr make install
However! Here is the difficult part... We already have a systemsettings program installed: the one installed by the Debian system in /usr/bin/systemsettings. So you will now find that we have a second one of our own in ~/kde4devel/root/bin/systemsettings.
The make install command copied more than only the executable file! It also copied e.g. ~/kde4devel/root/lib/kde4/kcm_randr.so. So when we start our "local" systemsettings program, we want to make sure it first finds the files it installed under ~/kde4devel/root, and not first the files installed by Debian under /usr.
We need to tell our current console session the additional KDE path where it needs to look for services and libraries and programs. This is done by filling in the KDEDIRS environment variable like this:
<syntaxhighlight lang="bash"> export KDEDIRS=$HOME/kde4devel/root
Now when we start the systemsettings module in this console session it will find the kcontrol configuration module located in ~/kde4devel/root/lib/kde4/kcm_randr.so before the one in ~/kde4devel/root/kde4/kcm_randr.so:
<syntaxhighlight lang="bash"> cd ~/kde4devel/root ./systemsettings
And you will now see your own compiled code in action!
Now you have completed compiling and running your own compiled code, you are ready to check out the other tutorials here and gain some deeper insights!