ubuntu安装qt5 Could not load the Qt platform plugin “xcb“ in ““ even though it was found.

每次在linux安装QT总是会出现各种问题，看了很多博客都不够全面，解决问题花了很大的精力，实属没必要。想写篇尽可能全面的博客记录下来。

QT版本：qt-opensource-linux-x64-5.12.10.run
ubantu版本：18.04桌面版

1、下载

下载地址：https://download.qt.io/archive/qt/5.12/

2、运行安装文件

注意：安装要在系统提供的终端上进行，xshell下无法安装成功

给qt-opensource-linux-x64-5.12.10.run执行权限

chmod +x qt-opensource-linux-x64-5.12.10.run

执行完毕后用ls命令查看qt-opensource-linux-x64-5.12.10.run，确认有执行权限

ls -l qt-opensource-linux-x64-5.12.10.run

此时权限如下所示

3、开始安装

为了跳过QT安装时的登陆账号步骤，安装之前先把网络断开，如果有账号可以不断网。
执行如下命令启动安装程序，安装过程不要关闭终端窗口

 ./qt-opensource-linux-x64-5.12.10.run

一路下一步，直到选择组件时，最好全选，否则根据用途自行选择

想了解各模块功能的同学，参看如下链接：
Qt Charts：https://blog.csdn.net/u011430225/article/details/79012904
Qt Data Visualization：同上
Qt Purchasing ：https://www.cnblogs.com/findumars/p/5574539.html
Virtual Keyboard：同上

安装完成后，就下而已在如下目录中找到QTCreator了（如果不是安装在home根目录，需要进入指定目录）

~/Qt5.12.10/Tools/QtCreator/bin$

4、安装完毕

此时，qt已经安装完毕，尝试启动qtcreator，在ubantu下时无法启动，出现如下问题

找不到xcb库

This application failed to start because it could not find or load the Qt platform plugin "xcb"
in "".Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, xcb.Reinstalling the application may fix this problem.
Aborted (core dumped)

解决方法：

解决方法：
1.sudo gedit ~/.bashrc 输入 export QT_DEBUG_PLUGINS=1 和
export LD_LIBRARY_PATH=/home/itcast/qt/Qt5.12.10/5.12.10/gcc_64/lib:$LD_LIBRARY_PATH（注意把路径替换为自己的安装路径）

2.运行qtcreator，在命令行得到运行中过程，如下

QFactoryLoader::QFactoryLoader() checking directory path "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqeglfs.so"
Found metadata in lib /home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqeglfs.so, metadata=
{"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3","MetaData": {"Keys": ["eglfs"]},"archreq": 0,"className": "QEglFSIntegrationPlugin","debug": false,"version": 331520
}Got keys from plugin meta data ("eglfs")
QFactoryLoader::QFactoryLoader() looking at "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqlinuxfb.so"
Found metadata in lib /home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqlinuxfb.so, metadata=
{"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3","MetaData": {"Keys": ["linuxfb"]},"archreq": 0,"className": "QLinuxFbIntegrationPlugin","debug": false,"version": 331520
}Got keys from plugin meta data ("linuxfb")
QFactoryLoader::QFactoryLoader() looking at "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqminimal.so"
Found metadata in lib /home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqminimal.so, metadata=
{"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3","MetaData": {"Keys": ["minimal"]},"archreq": 0,"className": "QMinimalIntegrationPlugin","debug": false,"version": 331520
}Got keys from plugin meta data ("minimal")
QFactoryLoader::QFactoryLoader() looking at "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqminimalegl.so"
Found metadata in lib /home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqminimalegl.so, metadata=
{"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3","MetaData": {"Keys": ["minimalegl"]},"archreq": 0,"className": "QMinimalEglIntegrationPlugin","debug": false,"version": 331520
}Got keys from plugin meta data ("minimalegl")
QFactoryLoader::QFactoryLoader() looking at "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqoffscreen.so"
Found metadata in lib /home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqoffscreen.so, metadata=
{"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3","MetaData": {"Keys": ["offscreen"]},"archreq": 0,"className": "QOffscreenIntegrationPlugin","debug": false,"version": 331520
}Got keys from plugin meta data ("offscreen")
QFactoryLoader::QFactoryLoader() looking at "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqvnc.so"
Found metadata in lib /home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqvnc.so, metadata=
{"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3","MetaData": {"Keys": ["vnc"]},"archreq": 0,"className": "QVncIntegrationPlugin","debug": false,"version": 331520
}Got keys from plugin meta data ("vnc")
QFactoryLoader::QFactoryLoader() looking at "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqxcb.so"
Found metadata in lib /home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqxcb.so, metadata=
{"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3","MetaData": {"Keys": ["xcb"]},"archreq": 0,"className": "QXcbIntegrationPlugin","debug": false,"version": 331520
}Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/bin/platforms" ...
loaded library "/home/itcast/qt/Qt5.12.10/Tools/QtCreator/lib/Qt/plugins/platforms/libqxcb.so"
loaded library "Xcursor"
Segmentation fault (core dumped)

3.原因在于libqxcb.so，解决方法：

进入platform目录 ： ~/qt/Qt5.12.10/5.12.10/gcc_64/plugins/platforms（注意路径和安装位置有关） 执行如下命令

ldd libqxcb.so

sudo apt install --reinstall libxcb-xinerama0

source ~/.bashrc

到这里QT就已经可以打开了（注意,QT 需要加sudo才能打开）

sudo ./qtcreator