qmake persistent property (environment variables) on Linux systems

Hello.

I'm trying to set the qmake persistent properties which is also called environment variables in order to use the older version of qt in qt creator.

Here is the relevant packages I have:
- Qt Creator 2.4.1 (Based on Qt 4.8.0 (32 bit))
- Qt 3.4.8b
- Qt 4.8.1

By default, Qt Creator uses Qt 4.8.1, but I need to change this to the older version of Qt (3.4.8b).
So I go to "Tools -> Options -> Build & Run -> Qt Versions" tab, and added qmake that is linked to the qmake-qt3.
(My system, Ubuntu 12.04, uses update-alternatives to maintain different versions of packages. So qmake is linked to the qmake-qt3.)

Anyway, that causes an error such as "Could not determine the path to the binaries of the Qt installation, maybe the qmake path is wrong?".
I googled the error message and found that this is because my qmake does not have its environment variables.
When I typed the command, '$ qmake -query', the result shows nothing while '$ qmake-qt4 -query' shows the below:

QT_INSTALL_PREFIX:/usr
QT_INSTALL_DATA:/usr/share/qt4
QT_INSTALL_DOCS:/usr/share/qt4/doc
QT_INSTALL_HEADERS:/usr/include/qt4
QT_INSTALL_LIBS:/usr/lib/i386-linux-gnu
QT_INSTALL_BINS:/usr/bin
QT_INSTALL_PLUGINS:/usr/lib/i386-linux-gnu/qt4/plugins
QT_INSTALL_IMPORTS:/usr/lib/qt4/imports
QT_INSTALL_TRANSLATIONS:/usr/share/qt4/translations
QT_INSTALL_CONFIGURATION:/etc/xdg
QT_INSTALL_EXAMPLES:/usr/lib/qt4/examples
QT_INSTALL_DEMOS:/usr/lib/qt4/demos
QMAKE_MKSPECS:/usr/share/qt4/mkspecs
QMAKE_VERSION:2.01a
QT_VERSION:4.8.1

Based on this, I tried to set the variables using 'qmake -set' command.
But... I made some typo... and resulted in adding wrong vaiables. My qmake (= qmake-qt3) persistent properties have the variables the below:

QT_INSTALL:
QT_INSTALL_PREFIX:
QT_NINSTALL_PREFIX:


I set the values as NULL using the command such as ' $ qmake -set QT_INSTALL "" '.
But I don't know how to remove those.

I tried to remove the package, qt3-dev-tools, from my system and install it agian, but it did not helped me.
I saw some postings about the qmake persistent properties, but I couldn't find any helpful articles till now.

So could anyone help me to remove these variables and start it over?

* Oh. I forgot telling that I installed my Qt3 and Qt4 via Ubuntu apt-get command.

Quote:

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Originally Posted by hwanud

So could anyone help me to remove these variables and start it over?

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Code:

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$ qmake -unset VARIABLE

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"qmake -h" is also useful

Thank you for yor reply.
I have tried that command, qmake -unset, but it did not work for me unfortunately.
Also I tried qmake -remove and -clear, but same result.
qmake -h does not give me any helpful options, too.

Did I miss something?

Qt 3.4.8? Wasn't the last Qt3 version 3.3.8?

By the way, qmake -set does not operate on environment variables, these are internal qmake variables. I don't think Qt3 used those, by the way. We only had $QTDIR (which indeed was an environment variable) there, as far as I remember.

Since the qmake syntax and the whole development approach in Qt3 was much different than Qt4, I doubt you will be able to force QtCreator to help you with such projects in any meaningful way. You can still use it as a rich code editor but you should manage the project yourself (you can still ask Creator to build the project for you though).

@wysota

Sorry, I made a mistake about the version. You're right. My Qt version is 3.3.8b.
Thank you.

For the use of Qt3 on Creator, your opinion looks right. Even though I force to set the all variables of qmake-qt3 to the values I have extracted from the result of 'qmake-qt4 -query', Creator does not work as I expected. Maybe it does not support lower version of Qt than Qt4.
As you told, it might be better to use the Creator as a rich code editor if I want to develop something using Qt3.

Thanks for your helpful advice!

Actually you are much better off not developing anything in Qt3 at all.

Thanks a lot.

Actually I am not developing my app from the beginning. I just want to use the simulator which is already developed based on Qt3.
With the Makefile provided for the simulator, I can compile and run the code without any problem, but the vi environment is not that comfortable for me yet.
This is why I want to use Creator.

I will use Qt4 when I make something for myself as you advised me.