The Qt package contains a C++ GUI library. This is useful for creating graphical applications or executing graphical applications that are dynamically linked to the Qt library. One of the major users of Qt is KDE.

There are several ways to install a complicated package such as Qt. The files are not completely position independent. Installation procedures execute the program pkg-config to determine the location of package executables, libraries, headers, and other files. For Qt, pkg-config will look for the file lib/pkgconfig/qt-mt.pc which must be modified if relocating the package. This file is set up correctly by the build process.

The default installation places the files in /usr/local/qt/. Many commercial distributions place the files in the system's /usr hierarchy. The package can also be installed in an arbitrary directory.

This section will demonstrate two different methods.

Note

The build time for Qt is quite long. If you want to save some time and don't want the tutorials and examples, change the first make line to:

make sub-tools

sed -i "s:cp -f:install:" mkspecs/linux-g++/qmake.conf &&
bash
export PATH=$PWD/bin:$PATH &&
export LD_LIBRARY_PATH=$PWD/lib:$LD_LIBRARY_PATH &&
./configure -prefix /usr -docdir /usr/share/doc/qt \
    -headerdir /usr/include/qt -plugindir /usr/lib/qt/plugins \
    -datadir /usr/share/qt -translationdir /usr/share/qt/translations \
    -sysconfdir /etc/qt -qt-gif -system-zlib -system-libmng \
    -no-exceptions -thread -plugin-imgfmt-png \
    -system-libjpeg -system-libpng &&
find -type f -name Makefile | xargs sed -i "s@-Wl,-rpath,/usr/lib@@g" &&
make &&
make install &&
ln -sf libqt-mt.so /usr/lib/libqt.so &&
rm /usr/bin/qmake &&
install -m755 -oroot -groot qmake/qmake /usr/bin &&
cp -r doc/man /usr/share &&
cp -r examples /usr/share/doc/qt &&
exit

Method 2 - Installing in /opt

This is the method recommended by the Qt developers. It has the advantage of keeping all the package files consolidated in a dedicated directory hierarchy. By using this method, an update can be made without overwriting a previous installation and users can easily revert to a previous version by changing one symbolic link.

The Qt developers use a default location of /usr/local/qt/, however this procedure puts the files in /opt/qt-3.3.3/ and then creates a symbolic link to /opt/qt/.

bash
export QTDIR=$PWD &&
export LD_LIBRARY_PATH=$PWD/lib:$LD_LIBRARY_PATH &&
export PATH=$PWD/bin:$PATH &&
./configure -prefix /opt/qt-3.3.3 -qt-gif -system-libpng \
    -system-libmng -system-zlib -system-libjpeg -no-exceptions \
    -thread -plugin-imgfmt-png &&
make &&
make install &&
ln -sfn qt-3.3.3 /opt/qt &&
ln -s libqt-mt.so /opt/qt/lib/libqt.so &&
rm /opt/qt-3.3.3/bin/qmake &&
install -m755 -oroot -groot qmake/qmake /opt/qt-3.3.3/bin &&
cp -r doc/man /opt/qt/doc &&
cp -r examples /opt/qt/doc
exit

Note

If you pass the -plugin-sql-[driver] switch to the configure command, you must also pass -I[/path/to/sql/headers] so make can find the appropriate header files.

sed -i "s:cp -f:install:" mkspecs/linux-g++/qmake.conf: install is safer than cp when libraries are in use.

bash: This command enters a sub-shell to isolate environment changes.

export QTDIR=$PWD: This command defines where the root of the Qt directory is located.

export LD_LIBRARY_PATH=$PWD/lib:$LD_LIBRARY_PATH: This command allows the not yet installed Qt libraries to be used by the not yet installed Qt programs.

export PATH=$PWD/bin:$PATH: This command allows the build process to find supporting executables.

-qt-gif: This switch adds support for gif files to the libraries.

-system-zlib -system-libpng: This switch forces the build instructions to use the shared libraries that are on your system instead of creating a custom set of support libraries for these functions.

-plugin-imgfmt-png: This switch enables libpng to be linked to at runtime.

-no-exceptions: This switch disables the exceptions coding generated by the C++ compiler.

-thread: This switch adds support for multi-threading.

find -type f -name Makefile | xargs sed -i "s@-Wl,-rpath,/usr/lib@@g": This command removes hardcoded run-time paths. Otherwise, uic always tries to run with Qt libraries in /usr/lib.

ln -s libqt-mt.so /usr/lib/libqt.so: This command allows configure scripts to find a working Qt installation.

rm .../qmake; install -m755 -oroot -groot qmake/qmake .../bin: The qmake program is installed incorrectly by make install. These two commands install the program correctly.

cp -r doc/man /usr/share (or /opt/qt/doc): This command installs the man pages which are missed by make install.

cp -r examples /usr/share/doc/qt (or /opt/qt/doc): This command installs the examples which are missed by make install.

exit: This command returns to the parent shell and eliminates environment variables set earlier.

The Qt/X11 library contains APIs necessary to use programs based on the Qt GUI toolkit.

The Qt package contains assistant, designer, linguist, lrelease, lupdate, moc, qm2ts, qmake, qtconfig, uic, and the libqt-mt and libqui libraries.