How can I correctly install qt5?

Question

I'm trying to upgrade from qt4 to qt5. I was following a guide and it appears I have managed to install qt5. As seen here...

daveomcd@ubuntu:~/Documents/rails_projects/bane$ dpkg -l qt5-qmake
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                                          Version                     Architecture                Description
+++-=============================================-===========================-===========================-================================================================================================
ii  qt5-qmake:amd64                               5.5.1+dfsg-16ubuntu7.1      amd64                       Qt 5 qmake Makefile generator tool

The guide mentioned doing rm 'which qmake' to remove the old install of qt4 at some point. But know the software I'm trying to use that relies on qmake is no longer working. I get the following error: Command 'qmake ' not available

Anyone know how I can resolve this issue? Also it seems qt4 is still installed as well. As seen below.

Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                                          Version                     Architecture                Description
+++-=============================================-===========================-===========================-================================================================================================
ii  qt4-qmake                                     4:4.8.7+dfsg-5ubuntu2       amd64                       Qt 4 qmake Makefile generator tool

Update: When I do... qtchooser -l I get the following:

4
5
default
qt4-x86_64-linux-gnu
qt4
qt5-x86_64-linux-gnu
qt5

Answer 1

Normally they exist simultaneously.

List available versions:

$ qtchooser -l
4
5
default
qt4-i386-linux-gnu
qt4-x86_64-linux-gnu
qt4
qt5-x86_64-linux-gnu
qt5.5-x86_64-linux-gnu
qt5

Find out where it is:

$ qtchooser -qt=4 -print-env
QT_SELECT="4"
QTTOOLDIR="/usr/lib/x86_64-linux-gnu/qt4/bin"
QTLIBDIR="/usr/lib/x86_64-linux-gnu"

Use it with qmake:

$ qmake -qt=5 --version
QMake version 3.0
Using Qt version 5.5.1 in /usr/lib/x86_64-linux-gnu

For CMake set CMAKE_PREFIX_PATH to things like /usr/lib/x86_64-linux-gnu/qt5/lib/cmake/ (for Qt installs from the package manager) or /data/qt/Qt-5.5/5.5/gcc_64/lib/cmake/ (that kind of structure comes from the manual installs).