In order to install THELI (GUI version) there is a series of libs and compilers to have already installed prior to THELI (like the fast-fourier transform (fftw), TIFF libraries (libtiff), C and C++ compilers (gcc, g++), Qt3, see the list at the site). Although everything was installed there was still an error in the installation process arising from the possible lack of qmake. The related command in the install.sh script was:
qmake -o Makefile theli.pro
The theli.pro existed, qmake was also present in the computer, so … what was wrong? Finally, Giannis Kapetanakis from the computer support pointed to the use of the full path of qmake. So the previous line should change to:
/usr/lib/qt-3.3/bin/qmake -o Makefile theli.pro
and everything worked properly!
Lesson learned: add the full paths of programs when everything seems to be in place but still they do not work!