docker exec

Basic Syntax

Key Options and Parameters

1. -d, --detach: Run command in the background.

   docker exec -d mycontainer touch /tmp/execWorks

2. -i, --interactive: Keep STDIN open even if not attached.

   docker exec -i mycontainer bash

3. -t, --tty: Allocate a pseudo-TTY.

   docker exec -t mycontainer bash

4. -u, --user: Username or UID to run the command as.

   docker exec -u root mycontainer bash

5. -e, --env: Set environment variables.

   docker exec -e "ENV_VAR=value" mycontainer bash

6. -w, --workdir: Working directory inside the container.

   docker exec -w /app mycontainer ls

Examples

1. Running a Command in a Container

   docker exec mycontainer ls /app

   This command lists the contents of the /app directory inside the container named mycontainer.

2. Running a Command in the Background

   docker exec -d mycontainer touch /tmp/execWorks

   This command creates a file named execWorks in the /tmp directory inside the container named mycontainer and runs in the background.

3. Running an Interactive Shell

   docker exec -it mycontainer bash

   This command starts an interactive bash shell inside the container named mycontainer.

4. Running a Command as a Different User

   docker exec -u root mycontainer bash

   This command starts a bash shell inside the container named mycontainer as the root user.

5. Setting Environment Variables

   docker exec -e "ENV_VAR=value" mycontainer printenv ENV_VAR

   This command sets the environment variable ENV_VAR to value and prints it inside the container named mycontainer.

6. Specifying a Working Directory

   docker exec -w /app mycontainer ls

   This command lists the contents of the /app directory inside the container named mycontainer.

Conclusion

The docker exec command is essential for running commands in a running container. Understanding its options and parameters allows you to effectively manage and interact with your Docker containers.