How to See Container Processes in Docker

To see processes running inside a Docker container, use the docker top <container_name_or_id> command which lists active processes. Alternatively, you can run docker exec <container> ps aux to execute process listing inside the container.

Syntax

The main command to view container processes is docker top. It shows the processes running inside a container.

• docker top <container_name_or_id>: Lists active processes inside the specified container.
• docker exec <container> ps aux: Runs the ps aux command inside the container to show detailed process info.

bash

docker top <container_name_or_id>
docker exec <container_name_or_id> ps aux

Example

This example shows how to list processes inside a running container named myapp. First, docker top lists the processes. Then, docker exec runs ps aux inside the container for detailed info.

bash

docker top myapp
docker exec myapp ps aux

Output

UID                 PID                 PPID                C                   STIME               TTY                 TIME                CMD
root                1234                1                   0                   10:00               ?                   00:00:00            /bin/sh -c myapp
root                1250                1234                0                   10:00               ?                   00:00:01            /usr/bin/myapp

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root      1234  0.0  0.1  18540  3200 ?        Ss   10:00   0:00 /bin/sh -c myapp
root      1250  0.1  0.5  50000 12000 ?        Sl   10:00   0:01 /usr/bin/myapp

Common Pitfalls

Common mistakes when viewing container processes include:

• Using docker top without specifying the correct container name or ID causes an error.
• Expecting docker top output to be identical to host ps output; it may differ by Docker version and platform.
• Not having the container running will cause commands to fail.
• Using docker exec requires the container to have the ps command installed; some minimal images may lack it.

Wrong: docker top wrong_container (container does not exist)

Right: docker top myapp (correct container name)

bash

docker top wrong_container
# Error: No such container: wrong_container

docker top myapp
# Lists processes inside 'myapp' container

Quick Reference

Summary of commands to see container processes:

Command	Description
docker top	Show active processes inside the container
docker exec ps aux	Run detailed process list inside the container
docker ps	List running containers to get container names or IDs

Key Takeaways

Use docker top <container> to quickly see running processes inside a container.

If you need detailed process info, run docker exec <container> ps aux.

Make sure the container is running and you use the correct container name or ID.

Some minimal containers may not have ps installed, so docker exec might fail.

Use docker ps to find container names or IDs before checking processes.