Docker Core Commands Explained

Docker commands follow a pattern where different verbs represent different lifecycle actions:

docker run: Creates AND starts a new container from an image
```
docker run --name my-container nginx
```
This is like saying "create a container and start it running"
docker create: Creates a container but doesn't start it
```
docker create --name my-container nginx
```
This just prepares the container without starting it
docker start: Starts an existing (created or stopped) container
```
docker start my-container
```
This is used to run a container that already exists
docker stop: Gracefully stops a running container
```
docker stop my-container
```
This sends a SIGTERM signal, giving the container time to shut down cleanly
docker kill: Forcefully stops a container (like unplugging a computer)
```
docker kill my-container
```
This sends a SIGKILL signal, forcing immediate termination
docker restart: Stops and then starts a container
```
docker restart my-container
```
This is equivalent to a stop followed by a start
docker rm: Removes a container (must be stopped first, unless forced with -f)
```
docker rm my-container
```
This deletes the container entirely

docker images or docker image ls: Lists all images
```
docker images
```
docker rmi or docker image rm: Removes an image
```
docker rmi nginx
```
docker pull: Downloads an image from a registry without creating a container
```
docker pull nginx
```
docker build: Creates a new image from a Dockerfile
```
docker build -t my-image .
```

docker ps: Shows running containers
```
docker ps
```
docker ps -a: Shows all containers (running and stopped)
```
docker ps -a
```
docker logs: Shows logs from a container
```
docker logs my-container
```
docker inspect: Shows detailed information about a container
```
docker inspect my-container
```

Getting Past "Image Name Already Exists" Error

The most direct solution is to:

Find the container with the conflicting name:
```
docker ps -a | grep your-container-name
```
Remove it:
```
docker rm your-container-name
```
Then try your docker run command again

Or, you can use the force flag to automatically replace the existing container:

docker run --force --name your-container-name your-image