Qmake cannot find libraries

[dhaus]

I am using Qt Creator 6.0.1 on linux (Cinnamon). I previously compiled and ran the same project without any issues, just using g++ and linking to the same libraries with pkg-config. I now want to use Qt just to make a GUI for my program.

I am unable to link 2 system libraries for my project in Qt Creator. No matter how I try to link them, qmake fails to build because it cannot find them. First, I tried using pkg-config by adding the following to my .pro file:

    QT_CONFIG -= no-pkg-config
    CONFIG += link_pkgconfig
    PKG_CONFIG_PATH=:/usr/lib/x86_64-linux-gnu/pkgconfig
    PKGCONFIG += sndfile
    PKGCONFIG += jack
    PKGCONFIG += soundtouch

But I just get a "jack development package not found" error message and it doesn't compile. Strangely, it finds sndfile, but not the other two. Also, it cannot find the system header files that I refer to, even if I explicitly put the full path from root in quotation marks. To troubleshoot, I tried using LIBS+=... and INCLUDEPATH+=... instead of pkg-config, but that didn't work either.

So then, just to get it to compile, I tried manually adding each library .so file using right-click "Add Library", but in the file browser that pops up, many of the libraries in my /usr/lib/x86_64-linux-gnu/ folder are simply not there! (I can clearly see them when I use the file manager). It seems to me that the problem is that for some reason certain files in the root directory are invisible to Qt Creator and qmake. If I copy these same files to my project folder in the home directory and try to add them there, I can add them just fine. Same story with the header files in usr/include/.

Does anyone know why this might be happening and how to fix it?

[Christian Ehrlicher]

@dhaus said in Qmake cannot find libraries:

PKG_CONFIG_PATH=:/usr/lib/x86_64-linux-gnu/pkgconfig

Are you sure the : before the path is correct?

[dhaus]

No, but I've tried without it and it makes no difference.

[seyed]

The PKG_CONFIG_PATH is an environment variable so you need to add it before running qmake.
So set it through Projects > Build Settings > Build Environment in QtCreator or set it through terminal before running qmake manually in terminal.

Then add following lines in your .pro file:

mac {
  #if you need to specify
  PKG_CONFIG = /usr/local/bin/pkg-config
}

#someone says this need in some Qt versions but not need in my Qt 5.12.12
QT_CONFIG -= no-pkg-config   

CONFIG += link_pkgconfig
PKGCONFIG += protobuf \
             grpc \
             grpc++

I can't find a way to set environment variable in .pro file. Can you do it?