roscore运行报错和rviz打开报错

1、roscore运行报错

报错内容：

Traceback (most recent call last):
  File "/opt/ros/melodic/bin/roscore", line 72, in
    import roslaunch
  File "/opt/ros/melodic/lib/python2.7/dist-packages/roslaunch/__init__.py", line 62, in
    from .scriptapi import ROSLaunch
  File "/opt/ros/melodic/lib/python2.7/dist-packages/roslaunch/scriptapi.py", line 42, in
    import roslaunch.parent
  File "/opt/ros/melodic/lib/python2.7/dist-packages/roslaunch/parent.py", line 54, in
    import roslaunch.server
  File "/opt/ros/melodic/lib/python2.7/dist-packages/roslaunch/server.py", line 79, in
    from rosgraph_msgs.msg import Log
  File "/opt/ros/eloquent/lib/python3.6/site-packages/rosgraph_msgs/msg/__init__.py", line 1, in
    from rosgraph_msgs.msg._clock import Clock  # noqa: F401
  File "/opt/ros/eloquent/lib/python3.6/site-packages/rosgraph_msgs/msg/_clock.py", line 56
    class Clock(metaclass=Metaclass_Clock):
                         ^
SyntaxError: invalid syntax
解决办法：

cd /opt/ros/melodic

source setup.bash

2、rviz运行报错，闪退

报错内容：

[ INFO] [1645687530.666154492]: rviz version 1.13.23
[ INFO] [1645687530.666203628]: compiled against Qt version 5.9.5
[ INFO] [1645687530.666211976]: compiled against OGRE version 1.9.0 (Ghadamon)
[ INFO] [1645687530.669179157]: Forcing OpenGl version 0.
[ INFO] [1645687532.074182707]: Stereo is NOT SUPPORTED
[ INFO] [1645687532.074248483]: OpenGL device: SVGA3D; build: RELEASE;  LLVM;
[ INFO] [1645687532.074262172]: OpenGl version: 3.3 (GLSL 3.3) limited to GLSL 1.4 on Mesa system.
rviz: symbol lookup error: /opt/ros/melodic/lib/libtf.so: undefined symbol: _ZN7tf2_ros6BufferC1EN3ros8DurationEb
查找问题：echo $LD_LIBRARY_PATH

/opt/ros/eloquent/opt/yaml_cpp_vendor/lib:/opt/ros/eloquent/opt/rviz_ogre_vendor/lib:/opt/ros/eloquent/lib/x86_64-linux-gnu:/opt/ros/eloquent/lib:/opt/ros/melodic/lib

问题分析：因为安装了ROS2（eloquent），导致环境变量被修改
解决办法：source setup.bash