docker exec

The command is strongly associated with the Docker Container Lifecycle.

The docker exec command allows you to interact with a running container or enter its shell. It is commonly used with the -it flags to enable interaction with the container’s input and output streams.

docker exec [options] container_id command

Example

In the following example, we will start by running a container with the redis image. This will create a container that will initially run redis-server.

docker run redis
# * monotonic clock: POSIX clock_gettime
# * Running mode=standalone, port=6379.
# * Server initialized
# * Ready to accept connections tcp

To use the redis functionality, we need to run redis-cli in the container shell and its environment. To do this, we create another terminal and check the continer_id using docker ps. Then we use docker exec -it with the retrieved container_id to call redis-cli in the container.

docker ps
# CONTAINER ID   IMAGE     COMMAND                  CREATED              STATUS              PORTS      NAMES
# 408ff5ce70cb   redis     "docker-entrypoint.s…"   About a minute ago   Up About a minute   6379/tcp   nice_dhawan
 
docker exec -it 408ff5ce70cb redis-cli
127.0.0.1:6379> set number 1
# OK
127.0.0.1:6379> get number
# "1"

References

• Docker and Kubernetes: The Complete Guide
• docker exec | Docker Docs