how to fix linker error in eclipse on linux

micha_eleric

@jsulm qt4 it is what i started with.

i also found:
sudo apt install qt4-dev-tools libqt4-dev libqt4-core libqt4-gui

which seems to be from:
https://askubuntu.com/questions/1274134/cannot-install-qt-4-on-ubuntu-20-04-quite-universal-circuit-simulator-qucs

this is last i found with qt*, if it is not installing qt4, then i guess my errors have been found

sudo apt-get install qt5-default
results:
qt5-default is already the newest version (5.12.8+dfsg-0ubuntu2.1).

however, there are no qt5 directory under /usr/include

JonB

@micha_eleric said in how to fix linker error in eclipse on linux:

@jsulm qt4 it is what i started with.

This is not a great/clear answer, as @jsulm is pointing out that Qt4 is very old. Do you have a choice to move to Qt5, or even (hesitantly!) Qt6?

micha_eleric

@JonB it seems i already installed qt5. just it is not showing up under /usr/include

jsulm

@micha_eleric said in how to fix linker error in eclipse on linux:

i already installed qt5

What exactly? Which qt5 packages?
" just it is not showing up under /usr/include" - as I already told you b efore the libraries will NOT show up in that directory. Search for the qt5 libs like I suggested before:

find /usr/lib -name *qt5*
find /usr/lib64 -name *qt5*

Don't forget to also change include folders in your set-up as currently you use qt4 include folder.

micha_eleric

@jsulm said in how to fix linker error in eclipse on linux:

find /usr/lib -name qt5

michaeleric@michaeleric-C7B250-CB-ML:/usr/lib$ find -name qt5
./qt5
./x86_64-linux-gnu/qt5
michaeleric@michaeleric-C7B250-CB-ML:/usr/lib$ cd /
michaeleric@michaeleric-C7B250-CB-ML:/$ cd /usr/lib64
michaeleric@michaeleric-C7B250-CB-ML:/usr/lib64$ find -name qt5
michaeleric@michaeleric-C7B250-CB-ML:/usr/lib64$

jsulm

@micha_eleric Please read again what I suggested (hint: * is important)...

micha_eleric

@jsulm the * was used, copied, pasted, but did not show on post.

jsulm

@micha_eleric Can you please answer questions?
I asked before: What exactly? Which qt5 packages?

micha_eleric

@jsulm sudo apt-get install qt5-default
from:
https://wiki.qt.io/Install_Qt_5_on_Ubuntu

jsulm

@micha_eleric On my Ubuntu machine Qt5 libs are in /lib/x86_64-linux-gnu
Like /lib/x86_64-linux-gnu/libQt5Widgets.so.5

JonB

@micha_eleric said in how to fix linker error in eclipse on linux:

@jsulm the * was used, copied, pasted, but did not show on post.

find /usr/lib -name *qt5*
find /usr/lib64 -name *qt5*

You must quote these from the shell's expansion:

find /usr/lib -name '*Qt5*'
find /usr/lib64 -name '*Qt5*'

Or you might find this useful:

locate Qt5

jsulm

@JonB It is Qt not qt in lib names, so was my mistake

JonB

@jsulm
I have edited my response to use Qt5. But the quoting is still necessary!? https://man7.org/linux/man-pages/man1/find.1.html :

The filename matching is performed
with the use of the fnmatch(3) library function. Don't
forget to enclose the pattern in quotes in order to
protect it from expansion by the shell.

micha_eleric

@jsulm michaeleric@michaeleric-C7B250-CB-ML:~$ find /usr/lib -name *Qt5 *
/usr/lib/python3/dist-packages/PyQt5
/usr/lib/python3/dist-packages/PyQt5-5.14.1.dist-info
/usr/lib/x86_64-linux-gnu/libQt5GlxSupport.a
/usr/lib/x86_64-linux-gnu/libQt5DBus.so.5
/usr/lib/x86_64-linux-gnu/libQt5MultimediaQuick.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5LinuxAccessibilitySupport.a
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.so.5
/usr/lib/x86_64-linux-gnu/libQt5ThemeSupport.a
/usr/lib/x86_64-linux-gnu/libQt5MultimediaQuick.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5XmlPatterns.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5AccessibilitySupport.a
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Designer.so.5
/usr/lib/x86_64-linux-gnu/libQt5Positioning.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Svg.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Positioning.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebChannel.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
/usr/lib/x86_64-linux-gnu/libQt5WebKitWidgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5QuickTemplates2.so.5
/usr/lib/x86_64-linux-gnu/libQt5Test.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5EdidSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Widgets.so
/usr/lib/x86_64-linux-gnu/libQt5PlatformCompositorSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.so
/usr/lib/x86_64-linux-gnu/libQt5Network.so
/usr/lib/x86_64-linux-gnu/libQt5Xml.so
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.so.5
/usr/lib/x86_64-linux-gnu/libQt5VulkanSupport.a
/usr/lib/x86_64-linux-gnu/libQt5Test.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5ThemeSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
/usr/lib/x86_64-linux-gnu/libQt5MultimediaWidgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5InputSupport.a
/usr/lib/x86_64-linux-gnu/libQt5GlxSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Positioning.so.5
/usr/lib/x86_64-linux-gnu/libQt5VulkanSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5X11Extras.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Script.so.5
/usr/lib/x86_64-linux-gnu/libQt5Core.so.5
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/data/cmake/Qt5PluginTarget.cmake.in
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/data/cmake/Qt5BasicConfig.cmake.in
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/features/data/cmake/Qt5ConfigVersion.cmake.in
/usr/lib/x86_64-linux-gnu/libQt5WaylandCompositor.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5KmsSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5WaylandCompositor.so.5
/usr/lib/x86_64-linux-gnu/libQt5WebEngine.so.5
/usr/lib/x86_64-linux-gnu/libQt5EventDispatcherSupport.a
/usr/lib/x86_64-linux-gnu/libQt5Script.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Test.prl
/usr/lib/x86_64-linux-gnu/libQt5DBus.so.5.12.8
/usr/lib/x86_64-linux-gnu/cmake/Qt5TextToSpeech
/usr/lib/x86_64-linux-gnu/cmake/Qt5TextToSpeech/Qt5TextToSpeech_QTextToSpeechEngineFlite.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGL
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGL/Qt5OpenGLConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGL/Qt5OpenGLConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5PrintSupport
/usr/lib/x86_64-linux-gnu/cmake/Qt5PrintSupport/Qt5PrintSupportConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5PrintSupport/Qt5PrintSupport_QCupsPrinterSupportPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5PrintSupport/Qt5PrintSupportConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Sql
/usr/lib/x86_64-linux-gnu/cmake/Qt5Sql/Qt5SqlConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Sql/Qt5SqlConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGLExtensions
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGLExtensions/Qt5OpenGLExtensionsConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5OpenGLExtensions/Qt5OpenGLExtensionsConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEvdevMousePlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QTuioTouchPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEvdevKeyboardPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QXcbIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSKmsGbmIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5GuiConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5GuiConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QXcbEglIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSKmsEglDeviceIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QComposePlatformInputContextPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QIbusPlatformInputContextPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QVncIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEvdevTouchScreenPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QXcbGlxIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEvdevTabletPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSX11IntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSEmulatorIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QGifPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QEglFSIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QMinimalIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QOffscreenIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QICOPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QMinimalEglIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QLinuxFbIntegrationPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QLibInputPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5Gui_QJpegPlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Gui/Qt5GuiConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5SerialPort
/usr/lib/x86_64-linux-gnu/cmake/Qt5SerialPort/Qt5SerialPortConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5SerialPort/Qt5SerialPortConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5Network_QGenericEnginePlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5NetworkConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5Network_QNetworkManagerEnginePlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5Network_QConnmanEnginePlugin.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Network/Qt5NetworkConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CTestMacros.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreMacros.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreConfigExtrasMkspecDir.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets/Qt5WidgetsMacros.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets/Qt5WidgetsConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets/Qt5WidgetsConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Widgets/Qt5WidgetsConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Test
/usr/lib/x86_64-linux-gnu/cmake/Qt5Test/Qt5TestConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Test/Qt5TestConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Test/Qt5TestConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Concurrent
/usr/lib/x86_64-linux-gnu/cmake/Qt5Concurrent/Qt5ConcurrentConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Concurrent/Qt5ConcurrentConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus/Qt5DBusConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus/Qt5DBusConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus/Qt5DBusMacros.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5DBus/Qt5DBusConfigExtras.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Xml
/usr/lib/x86_64-linux-gnu/cmake/Qt5Xml/Qt5XmlConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5Xml/Qt5XmlConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5
/usr/lib/x86_64-linux-gnu/cmake/Qt5/Qt5ConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5/Qt5ModuleLocation.cmake
/usr/lib/x86_64-linux-gnu/cmake/Qt5/Qt5Config.cmake
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Xml.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Widgets.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Test.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Sql.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Core.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5SerialPort.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Concurrent.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Gui.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5Network.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5DBus.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5PrintSupport.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5OpenGLExtensions.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/Qt5OpenGL.pc
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Xml.so.5
/usr/lib/x86_64-linux-gnu/libQt5MultimediaGstTools.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WebEngineWidgets.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5HunspellInputMethod.so.5
/usr/lib/x86_64-linux-gnu/libQt5Svg.so.5
/usr/lib/x86_64-linux-gnu/libQt5MultimediaGstTools.so.5
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.so.5
/usr/lib/x86_64-linux-gnu/libQt5Gui.prl
/usr/lib/x86_64-linux-gnu/libQt5QuickWidgets.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5DeviceDiscoverySupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Sql.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.so.5
/usr/lib/x86_64-linux-gnu/libQt5EventDispatcherSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Help.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Network.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Qml.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Multimedia.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Sql.so.5
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WebEngineWidgets.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so
/usr/lib/x86_64-linux-gnu/libQt5WebEngine.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Network.so.5
/usr/lib/x86_64-linux-gnu/libQt5QuickControls2.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
/usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
/usr/lib/x86_64-linux-gnu/libQt5QuickControls2.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5XmlPatterns.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Xml.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5EglSupport.a
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.so
/usr/lib/x86_64-linux-gnu/libQt5DBus.prl
/usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5TextToSpeech.so.5
/usr/lib/x86_64-linux-gnu/libQt5Xml.prl
/usr/lib/x86_64-linux-gnu/libQt5AccessibilitySupport.prl
/usr/lib/x86_64-linux-gnu/libQt5WebEngineCore.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5PlatformCompositorSupport.a
/usr/lib/x86_64-linux-gnu/libQt5WaylandCompositor.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Core.prl
/usr/lib/x86_64-linux-gnu/libQt5Core.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5FbSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Script.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Help.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5ServiceSupport.a
/usr/lib/x86_64-linux-gnu/libQt5VirtualKeyboard.so.5
/usr/lib/x86_64-linux-gnu/libQt5Help.so.5
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.prl
/usr/lib/x86_64-linux-gnu/libQt5Test.so
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebEngineCore.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5MultimediaGstTools.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WebEngineWidgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5Designer.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WaylandClient.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5DBus.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Network.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5VirtualKeyboard.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Quick.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5FontDatabaseSupport.a
/usr/lib/x86_64-linux-gnu/libQt5QuickTemplates2.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.so
/usr/lib/x86_64-linux-gnu/libQt5Sql.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5QuickTemplates2.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5VirtualKeyboard.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Gui.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Network.prl
/usr/lib/x86_64-linux-gnu/libQt5WaylandClient.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5QuickWidgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5Quick.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5WaylandClient.so.5
/usr/lib/x86_64-linux-gnu/libQt5HunspellInputMethod.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Gui.so
/usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
/usr/lib/x86_64-linux-gnu/libQt5HunspellInputMethod.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Sensors.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.so
/usr/lib/x86_64-linux-gnu/libQt5Xml.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5TextToSpeech.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebEngine.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5WebChannel.so.5
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Core.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Core.so
/usr/lib/x86_64-linux-gnu/libQt5MultimediaWidgets.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5EglFsKmsSupport.so
/usr/lib/x86_64-linux-gnu/libQt5Sql.so
/usr/lib/x86_64-linux-gnu/libQt5EdidSupport.a
/usr/lib/x86_64-linux-gnu/libQt5DeviceDiscoverySupport.a
/usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5.212.0
/usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
/usr/lib/x86_64-linux-gnu/libQt5X11Extras.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5QuickControls2.so.5
/usr/lib/x86_64-linux-gnu/libQt5InputSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5MultimediaQuick.so.5
/usr/lib/x86_64-linux-gnu/libQt5Test.so.5
/usr/lib/x86_64-linux-gnu/libQt5FontDatabaseSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5OpenGLExtensions.prl
/usr/lib/x86_64-linux-gnu/libQt5SerialPort.prl
/usr/lib/x86_64-linux-gnu/libQt5Sql.prl
/usr/lib/x86_64-linux-gnu/libQt5XmlPatterns.so.5
/usr/lib/x86_64-linux-gnu/libQt5Sensors.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5MultimediaWidgets.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5XcbQpa.prl
/usr/lib/x86_64-linux-gnu/libQt5WebChannel.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Svg.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Multimedia.so.5
/usr/lib/x86_64-linux-gnu/libQt5WebKitWidgets.so.5.212.0
/usr/lib/x86_64-linux-gnu/libQt5Qml.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5Concurrent.prl
/usr/lib/x86_64-linux-gnu/libQt5Sensors.so.5
/usr/lib/x86_64-linux-gnu/libQt5FbSupport.a
/usr/lib/x86_64-linux-gnu/libQt5Designer.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5ServiceSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5OpenGLExtensions.a
/usr/lib/x86_64-linux-gnu/libQt5QuickWidgets.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5Widgets.prl
/usr/lib/x86_64-linux-gnu/libQt5Multimedia.so.5.12.8
/usr/lib/x86_64-linux-gnu/libQt5LinuxAccessibilitySupport.prl
/usr/lib/x86_64-linux-gnu/libQt5X11Extras.so.5
/usr/lib/x86_64-linux-gnu/libQt5TextToSpeech.so.5.12
/usr/lib/x86_64-linux-gnu/libQt5DBus.so
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.so
/usr/lib/x86_64-linux-gnu/libQt5WebEngineCore.so.5
/usr/lib/x86_64-linux-gnu/libQt5PrintSupport.so.5
/usr/lib/x86_64-linux-gnu/libQt5EglFSDeviceIntegration.prl
/usr/lib/x86_64-linux-gnu/libQt5KmsSupport.a
/usr/lib/x86_64-linux-gnu/libQt5OpenGL.so.5
/usr/lib/x86_64-linux-gnu/libQt5EglSupport.prl
/usr/lib/x86_64-linux-gnu/libQt5Gui.so.5.12
michaeleric@michaeleric-C7B250-CB-ML:~$

jsulm

@micha_eleric So, now you know in which folder the Qt libs are located

jsulm

@JonB said in how to fix linker error in eclipse on linux:

But the quoting is still necessary!?

For me both work on Ubuntu with GNU find (both have same amount of matches)

JonB

@jsulm
Sorry I cannot leave this statement as-is! As we discussed privately, your unquoted behaviour of *Qt* will generate totally different results depending on whether the current directory does or does not contain any filenames matching *Qt*. Which is not what is desired for this search. ALWAYS quote wildcards (*, ?) you are passing to a command like find if you expect it to work correctly robustly.... :)

P.S.
If anyone does not believe me: before running the command do a touch Qt5 in the directory you run find /usr/lib -name '*Qt5*' versus find /usr/lib -name *Qt5* from., and compare the results...

micha_eleric

@JonB for me, find /usr/lib -name'*Qt5 *', anr find /usr/lib -name *Qt5 * had same results. [note] no space between 5 and *

micha_eleric

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) /usr/lib/x86_64-linux-gnu
/usr/bin/ld: cannot find -l/usr/lib/x86_64-linux-gnu
under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) /usr/lib/x86_64-linux-gnu/qt5
/usr/bin/ld: cannot find -l/usr/lib/x86_64-linux-gnu/qt5

both have libraries, but no clue if i have to add a specific file, or just the dir it is in

under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) /usr/lib/x86_64-linux-gnu/libQtCore
/usr/bin/ld: cannot find -l/usr/lib/x86_64-linux-gnu/libQtCore
under Properties->C/C++ Build->Settings->Tool Settings->GCC C++ Linker->Libraries->Libraries (-l) /usr/lib/x86_64-linux-gnu/libQtCore.so
/usr/bin/ld: cannot find -l/usr/lib/x86_64-linux-gnu/libQtCore.so

it can not find a library, so i have to be doing something wrong

micha_eleric

michaeleric@michaeleric-C7B250-CB-ML:~$ sudo find / -name '*MainWindow *'
[sudo] password for michaeleric:
/home/michaeleric/eclipse-workspace/GUI/CUi_MainWindow.h
find: ‘/run/user/1000/doc’: Permission denied
/usr/share/doc/HTML/ca/spectacle/MainWindow.png
/usr/share/doc/HTML/uk/spectacle/MainWindow.png
/usr/share/doc/HTML/en/spectacle/MainWindow.png
/usr/include/qt4/Qt3Support/Q3MainWindow
/usr/include/qt4/QtGui/QMainWindow
/usr/include/x86_64-linux-gnu/qt5/QtWidgets/QMainWindow
michaeleric@michaeleric-C7B250-CB-ML:~$

there are no .h files for QMainWindow under Qt5 anywhere, thus why i was using Qt4, and thought Qt4 was installed.
error is about undefined reference to `QMainWindow:
i am looking around for a needle in a haystack, but dont know what the needle looks like, nor which haystack