How to solve the problem that docker is not an internal command

With the development of cloud computing, virtualization technology has attracted more and more attention. As an implementation of lightweight container technology, Docker technology is favored by many developers and server administrators. However, some people may encounter problems such as "docker is not an internal command nor an external command" when using Docker. So, what is the problem? Why does it happen? How to solve?

Source of the problem

Docker is a virtualization technology that can package an application and its dependent software into a container, so that the application can run in different environments without affected. When using Docker, we need to enter some instructions through the command line to manage the container. However, when some people use Docker for the first time, an error message "docker is not an internal or external command" may appear.

This problem is usually caused by the computer not recognizing Docker commands. When we enter a Docker command on the command line, the system will look for the location of the command in the environment variable $PATH. If it cannot be found, an error message "Not an internal command" will appear.

Solution

By adding the path

To solve this problem, the easiest way is to add the path of Docker to the environment variable $PATH. This way, the computer can look for Docker commands in this path.

Taking Windows system as an example, you can press the win Pause/Break key combination to open the system properties panel, and then select "Advanced System Settings". In the Advanced tab, select Environment Variables. Find $PATH in "System Variables" (if it is not found, you need to create a new one), and then add the Docker installation path to the end of the variable value. Generally, the installation path of Docker is C:\Program Files\Docker\Docker\resources\bin. After adding, you need to log out and log in again to the system to take effect.

By setting environment variables

Another method is to create a new variable in the environment variable and use the Docker installation path as the variable value. Taking the Linux system as an example, you can open a terminal and enter the command sudo gedit /etc/environment. Create a new variable in the opened file with the name PATH_TO_DOCKER and the value is the installation path of Docker.

LANG=en_US.UTF-8
LC_ALL=en_US.UTF-8
PATH="$PATH:/usr/local/bin:/usr/sbin:/usr/bin:/ sbin:/bin:/usr/games"
PATH_TO_DOCKER="/usr/bin/docker"

Save and exit the file, then enter source /etc/environment in the terminal to make the variables effective immediately.

By reinstalling

If the above two solutions cannot solve the problem, then it may be because Docker is not installed properly. In this case, we can try to uninstall Docker and reinstall it. For specific methods, please refer to Docker official documentation.

Conclusion

Docker is a virtualization technology widely used in cloud computing, containerization and other fields. When we find the problem "docker is not an internal command or an external command" when using Docker, it can be solved by adding a path, setting environment variables, or reinstalling Docker. At the same time, we also need to pay attention to following the correct operating procedures when using Docker to avoid other problems.

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