ubuntu@linux:~/Downloads/texmaker-4.5$ ./BUILD.sh
Texmaker compilation :
----------------------------------------
Enter path to QT:
/usr/bin/qtpaths
Enter SYSTEM (1: UNIX ; 2: MACOSX) :
1
Enter PREFIX (/usr , /usr/local or /opt) :
/opt
Enter  DIRECTORY for the desktop file (/usr/share/applications) :

Enter  DIRECTORY for the icon file (/usr/share/pixmaps) :

./BUILD.sh: 20: ./BUILD.sh: /usr/bin/qtpaths/bin/qmake: not found
make: *** No targets specified and no makefile found.  Stop.
make: *** No rule to make target 'install'.  Stop.
Compilation and installation done