[ROS] The difference between roscd and cd

Linux: Ubuntu 18.04 (Bionic)
ROS: ROS Melodic Morenia

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1. The difference between roscd and cd

cd, change directory, change directory.Both roscd and cd commands are used to switch to the specified directory.The differences between them are:

• cd is the command for UNIX/Linux systems;
• roscd is a command of the ROS system and is part of the rosbash command set; roscd can only switch to those paths already included in >ROS_PACKAGE_PATH package in the environment variable.

2. Example

   assumes you have created a catkin workspace and a catkin package named beginner_tutorials.

cd ~/catkin_ws/src/beginner_tutorials/

roscd beginner_tutorials

By comparison, roscd is faster to enter commands than cd.

3. Notes

   If roscd prompts something like roscd: No such package/stack 'beginner_tutorials', you need to create catkin workspaceThe following steps make the environment variables take effect:

cd ~/catkin_wssource devel/setup.bashroscd beginner_tutorials

  But every time you compile catkin_make, you must use source devel/setup.bash to refresh the environment, otherwise the above problem will occur.How to solve this problem?It's actually very simple, just add the source ~/catkin_ws/devel/setup.bash command to the .bashrc script file, and let the system automatically refresh the workspace.

echo “source ~/catkin_ws/devel/setup.bash” >> ~/.bashrc

   We can open the bashrc file with the following command, the source ~/catkin_ws/devel/setup.bash command is in the last line of the script.

gedit ~/.bashrc

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4. References

[1] ROS.org. ROS Tutorial [EB/OL]. [2022-6-29]. http://wiki.ros.org/en/ROS/Tutorials