Generally, when I want to explore the file system of a Docker container, I do it interactively by executing a shell inside it, something like:

$ docker exec -it container_name sh
$ ls

But sometimes the image of the container I want to explore does not contain any tools for this purpose. No ls, no cat, not even a shell. It is especially the case when building Docker images from scratch, which is very common with multi-stage builds.

One solution is to rely on the docker export tool which allows to "export a container's filesystem as a tar archive". By default, it writes the tar archive to STDOUT, which means it can be easily piped into the tar command-line tool to list its contents on the fly:

$ docker export 7c1f2edd42c4 | tar -tv | tee filesystem.txt
-rwxr-xr-x root/root         0 2022-04-04 09:46 .dockerenv
drwxr-xr-x root/root         0 2022-03-19 15:52 bin/
-rwxr-xr-x root/root  45687736 2022-03-19 15:52 bin/node