&kdesrc-build; supports building the &Qt; toolkit used by &kde; software as a convenience to users. This support is handled by a special module named qt. &Qt; is developed under a separate repository from &kde; software located at http://code.qt.io/cgit/qt/. In order to build &Qt;, you should make sure that the qt-install-dir option is set to the directory you'd like to install &Qt; to, as described in . You should then ensure that the qt module is added to your .kdesrc-buildrc, before any other modules in the file. If you are using the sample configuration file, you can simply uncomment the existing qt module entry. Now you should verify the repository option and branch options are set appropriately: The first option is to build &Qt; using a mirror maintained on the &kde; source repositories (no other changes are applied, it is simply a clone of the official source). This is highly recommended due to occasional issues with cloning the full &Qt; module from its official repository. You can set the repository option for the qt module to kde:qt to use this option. Otherwise, to build the standard &Qt;, set your repository option to git://gitorious.org/qt/qt.git. Note that you may experience problems performing the initial clone of &Qt; from this repository. In both cases, the branch option should be set to master (unless you'd like to build a different branch). Nota Bene: this section does not apply to modules for which you have configured a custom toolchain, using e.g. cmake-toolchain. To save you time, &kdesrc-build; adds some standard paths to your environment for you: The path to the &kde; and &Qt; libraries is added to the LD_LIBRARY_PATH variable automatically. This means that you do not need to edit &libpath; to include them. The path to the &kde; and &Qt; development support programs are added to the PATH variable automatically. This means that you do not need to edit &binpath; to include them. The path to the &kde;-provided pkg-config is added automatically to PKG_CONFIG_PATH. This means that you do not need to use &set-env; to add these. Programs can run with different priority levels on Operating Systems, including &Linux; and &BSD;. This allows the system to allocate time for the different programs in accordance with how important they are. &kdesrc-build; will normally allocate itself a low priority so that the rest of the programs on your system are unaffected and can run normally. Using this technique, &kdesrc-build; will use extra CPU when it is available. &kdesrc-build; will still maintain a high enough priority level so that it runs before routine batch processes and before CPU donation programs such as Seti@Home. To alter &kdesrc-build; so that it uses a higher (or lower) priority level permanently, then you need to adjust the &niceness; setting in the configuration file. The &niceness; setting controls how nice &kdesrc-build; is to other programs. In other words, having a higher &niceness; gives &kdesrc-build; a lower priority. So to give &kdesrc-build; a higher priority, reduce the &niceness; (and vice versa). The &niceness; can go from 0 (not nice at all, highest priority) to 20 (super nice, lowest priority). You can also temporarily change the priority for &kdesrc-build; by using the &cmd-nice; command line option. The value to the option is used exactly the same as for &niceness;. It is possible for some programs run by the super user to have a negative nice value, with a correspondingly even higher priority for such programs. Setting a negative (or even 0) &niceness; for &kdesrc-build; is not a great idea, as it will not help run time significantly, but will make your computer seem very sluggish should you still need to use it. To run &kdesrc-build; with a niceness of 15 (a lower priority than normal): % kdesrc-build --nice=15 Or, you can edit the configuration file to make the change permanent: &niceness; 15 The niceness option only affects the usage of the computer's processor(s). One other major affect on computer performance relates to how much data input or output (I/O) a program uses. In order to control how much I/O a program can use, modern &Linux; operating systems support a similar tool called ionice. &kdesrc-build; supports ionice, (but only to enable or disable it completely) using the use-idle-io-priority option, since &kdesrc-build; version 1.12. You may wish to have &kdesrc-build; run the installation with super user privileges. This may be for the unrecommended system-wide installation. This is also useful when using a recommended single user &kde; build, however. This is because some modules (especially kdebase) install programs that will briefly need elevated permissions when run. They are not able to achieve these permission levels unless they are installed with the elevated permissions. You could simply run &kdesrc-build; as the super user directly, but this is not recommended, since the program has not been audited for that kind of use. Although it should be safe to run the program in this fashion, it is better to avoid running as the super user when possible. To take care of this, &kdesrc-build; provides the &make-install-prefix; option. You can use this option to specify a command to use to perform the installation as another user. The recommended way to use this command is with the &sudo; program, which will run the install command as the super user. For example, to install all modules using &sudo;, you could do something like this: global &make-install-prefix; sudo # Other options end global To use &make-install-prefix; for only a single module, this would work: module some-module-name &make-install-prefix; sudo end module This feature is always available, and is automatically enabled when possible. What this does is display an estimated build progress while building a module; that way you know about how much longer it will take to build a module.