Ubuntu 20.4中无法打开rqt_graph的问题求助

运行rqt_graph时出现如下错误：

Traceback (most recent call last):
  File "/opt/ros/noetic/bin/rqt_graph", line 8, in <module>
    sys.exit(main.main(sys.argv, standalone='rqt_graph.ros_graph.RosGraph'))
  File "/opt/ros/noetic/lib/python3/dist-packages/rqt_gui/main.py", line 61, in main
    return super(
  File "/opt/ros/noetic/lib/python3/dist-packages/qt_gui/main.py", line 407, in main
    from python_qt_binding import QT_BINDING
  File "/opt/ros/noetic/lib/python3/dist-packages/python_qt_binding/__init__.py", line 55, in <module>
    from .binding_helper import loadUi, QT_BINDING, QT_BINDING_MODULES, QT_BINDING_VERSION  # @UnusedImport
  File "/opt/ros/noetic/lib/python3/dist-packages/python_qt_binding/binding_helper.py", line 274, in <module>
    _select_qt_binding(
  File "/opt/ros/noetic/lib/python3/dist-packages/python_qt_binding/binding_helper.py", line 118, in _select_qt_binding
    raise ImportError(
ImportError: Could not find Qt binding (looked for: 'pyqt', 'pyside'):
  ImportError for 'pyqt': libQt5Core.so.5: cannot open shared object file: No such file or directory
Traceback (most recent call last):
  File "/opt/ros/noetic/lib/python3/dist-packages/python_qt_binding/binding_helper.py", line 108, in _select_qt_binding
    QT_BINDING_VERSION = binding_loader(required_modules, optional_modules)
  File "/opt/ros/noetic/lib/python3/dist-packages/python_qt_binding/binding_helper.py", line 153, in _load_pyqt
    _named_import('PyQt5.%s' % module_name)
  File "/opt/ros/noetic/lib/python3/dist-packages/python_qt_binding/binding_helper.py", line 133, in _named_import
    module = builtins.__import__(name)
ImportError: libQt5Core.so.5: cannot open shared object file: No such file or directory

  ImportError for 'pyside': libQt5Core.so.5: cannot open shared object file: No such file or directory
Traceback (most recent call last):
  File "/opt/ros/noetic/lib/python3/dist-packages/python_qt_binding/binding_helper.py", line 108, in _select_qt_binding
    QT_BINDING_VERSION = binding_loader(required_modules, optional_modules)
  File "/opt/ros/noetic/lib/python3/dist-packages/python_qt_binding/binding_helper.py", line 185, in _load_pyside
    _named_import('PySide2.%s' % module_name)
  File "/opt/ros/noetic/lib/python3/dist-packages/python_qt_binding/binding_helper.py", line 133, in _named_import
    module = builtins.__import__(name)
ImportError: libQt5Core.so.5: cannot open shared object file: No such file or directory

已尝试的无效操作 #

• 重装libqt5相关系统包
• 执行sudo strip修复库的方案，执行后出现新的Qt库相关错误

解决方案建议 #

1. 定位并修复Qt5库路径 #

首先查找libQt5Core.so.5的安装位置：

sudo find / -name libQt5Core.so.5 2>/dev/null

• 如果找到路径（比如/usr/lib/x86_64-linux-gnu/libQt5Core.so.5），临时将其添加到系统库路径：

  export LD_LIBRARY_PATH=/usr/lib/x86_64-linux-gnu:$LD_LIBRARY_PATH
  

  想要永久生效，将上述命令添加到~/.bashrc文件末尾，然后执行source ~/.bashrc。
• 如果未找到该文件，安装完整的Qt5基础库：

  sudo apt install qtbase5-dev qt5-default
  

2. 修复ROS Qt绑定依赖 #

重新安装ROS相关的Qt绑定包：

sudo apt install --reinstall ros-noetic-python-qt-binding ros-noetic-rqt-gui ros-noetic-rqt-gui-py

同时修复系统中可能损坏的包：

sudo apt --fix-broken install
sudo apt update && sudo apt upgrade

3. 修复strip导致的库损坏 #

由于sudo strip可能破坏了Qt库的符号表，重新安装对应的Qt库包：
先查找libQt5Core.so.5所属的系统包：

dpkg -S libQt5Core.so.5

通常该文件属于libqt5core5a，执行重装：

sudo apt install --reinstall libqt5core5a

4. 验证Python Qt绑定 #

分别测试PyQt5和PySide2是否能正常导入：

• 测试PyQt5：

  python3 -c "import PyQt5.QtCore"
  

  若报错，重装PyQt5：

  sudo apt install python3-pyqt5
  

• 测试PySide2：

  python3 -c "import PySide2.QtCore"
  

  若报错，安装对应的包：

  sudo apt install python3-pyside2.qtcore
  

5. 确认ROS环境变量 #

确保每次启动终端都已加载ROS环境变量：

source /opt/ros/noetic/setup.bash

想要永久生效，将该命令添加到~/.bashrc文件末尾。

内容的提问来源于stack exchange，提问作者Niescte