一、安装
卸载旧版本Qt,找到安装目录，例如：/home/likewei/Qt5.11.2，终端输入命令进入该目录，输入命令：./MaintenanceTool 进入图形画面卸载就行了
1.下载安装文件，如：qt-opensource-linux-x64-5.11.2.run
2.打开终端（快捷键ctrl+alt+t），使安装文件可以执行，在当前目录输入命令 sudo chmod u+x qt-opensource-linux-x64-5.11.2.run
3.可以点击qt-opensource-linux-x64-5.11.2.run 安装。
4.apt-get安装源替换 阿里云源，否则安装的时候会出现“破坏了软件包间的依赖关系”等等错误。
编辑sources.list
sudo vim /etc/apt/sources.list
用下面的文本作为内容替换sources.list内容
ubuntu 14
deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
ubuntu 16
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse ##测试版源 deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse # 源码 deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse ##测试版源 deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse # Canonical 合作伙伴和附加 deb http://archive.canonical.com/ubuntu/ xenial partner deb http://extras.ubuntu.com/ubuntu/ xenial main
5.输入命令安装g++, sudo apt-get install g++
默认ubuntu14的gcc版本是4.8,支持c++11, 不支持c++14,安装g++ 5
5.1添加库
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
5.2 更新库
sudo apt-get update
5.3 安装
sudo apt-get install gcc-5 g++-5
5.4换软连接
sudo ln -s /usr/bin/gcc-5 /usr/bin/gcc -f
sudo ln -s /usr/bin/gcc-ar-5 /usr/bin/gcc-ar -f
sudo ln -s /usr/bin/gcc-nm /usr/bin/gcc-nm -f
sudo ln -s /usr/bin/g++-nm /usr/bin/g++-nm -f
sudo ln -s /usr/bin/g++-ar-5 /usr/bin/g++-ar -f
sudo ln -s /usr/bin/g++-5 /usr/bin/g++ -f
再查看版本 gcc -v
6.如果系统没有安装vim,输入命令安装，sudo apt-get install vim-gtk
7.输入qmake会出错：qmake:could not exec ‘/usr/lib/x86_64-linux-gnu/qt4/bin/qmake’:NO such file or directory（32位的ubuntu报的是这样的错 qmake:could not exec ‘/usr/lib/i386-linux-gnu/qt4/bin/qmake’:NO such file or directory）
修改文件：输入 sudo vim /usr/lib/x86_64-linux-gnu/qt-default/qtchooser/default.conf
修改前两行，根据qt安装文件路径修改成：
/home/likewei/Qt5.11.2/5.11.2/gcc_64/bin
/home/likewei/Qt5.11.2/5.11.2/gcc_64
vim编辑备忘：输入i进入插入模式，移动鼠标删除，编辑。输入esc退出当前模式，输入:进入命令模式。:w保存。
8.安装libgl1-mesa-dev ，否则在编译时会出错，提示
cannot find -lGL
collect2:error:ld returned 1 exit status
sudo apt-get install libgl1-mesa-dev
其他：
安装jsoncpp:
sudo apt-get install libjsoncpp-dev
二、ubuntu建立qt的默认打开方式
设置pro文件默认打开方式为qtcreator的方法如下：
1.建立软链接
sudo ln -s /home/likewei/Qt5.12.1/Tools/QtCreator/bin/qtcreator /usr/local/bin/qtcreator
如果已经建立了加参数-f,-f 建立时，将同档案名删除.
sudo ln -s -f /home/likewei/Qt5.12.1/Tools/QtCreator/bin/qtcreator /usr/local/bin/qtcreator
2.建立qtcreator.desktop
sudo vim /usr/share/applications/qtcreator.desktop
复制以下内容,修改图标位置，可以在网上下载一个图标： [Desktop Entry] Name = Qt Creator Comment = Open qt pro file Exec = qtcreator %U Terminal = false StartupNotify = true X-MultipleArgs = false Type = Application Categories = Utility; Icon = /home/likewei/图片/appimg/Qt.png
Icon=// 软件图标位置，可以自己选一个png图像，把png图像的绝对路径放这就可以
三、解决Qt不能输入中文注释问题
在/usr/lib/x86_64-linux-gnu/qt5/plugins/platforminputcontexts/libfcitxplatforminputcontextplugin.so 找到libfcitxplatforminputcontextplugin.so 。把此库文件复制到
以下Qt安装文件两个目录下面。
/home/likewei/Qt5.12.1/5.12.1/gcc_64/plugins/platforminputcontexts
/home/likewei/Qt5.12.1/Tools/QtCreator/lib/Qt/plugins/platforminputcontexts