ROS _common_issues.md

ROS - Common Issues

Problem

roscd \ rosls \ rosrun commands not found

Solution:

Install rosbash package.

sudo apt install ros-noetic-rosbash

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Problem

CMake Error at /opt/ros/noetic/share/catkin/cmake/empy.cmake:30 (message): Unable to find either executable 'empy' or Python module 'em'... try installing the package 'python-empy

Solution

1. Make sure you're using python 3 not python 2.

2. Ensure you're using your system's python installation to run ROS, not python from a conda environment. You can check the currently used python executable path by running

which python

3. Install python3-empy package. (Do not install empy via pip, install using apt package manager using below command)

sudo apt install python3-empy

Related answer on ROS Wiki

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Problem

Command not found: roscore

Solution:

Install package ros-noetic-roslaunch package.

sudo apt install ros-noetic-roslaunch