Docker · Reference

Inspect & exec cheat sheet

Compressed facts from lesson 0003. Keep open while debugging.

Jobs

Command	Does
`docker inspect`	Low-level JSON (config, state, networks)
`inspect -f '…'`	Go template — print one field / slice
`docker exec`	New command in a running container
`exec -it … sh`	Interactive shell (−i STDIN, −t TTY)

Debug ladder

docker ps / ps -a — running or exited?
docker logs name — stdout / stderr of main process
docker inspect name — full config / state
docker exec … — live filesystem / processes inside

Commands

# Running container required for exec
docker run -d -p 8080:80 --name lesson3 nginx:alpine

# Blueprint
docker inspect lesson3
docker inspect -f '{{.Config.Image}}' lesson3
docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' lesson3
docker inspect -f '{{json .Config}}' lesson3

# Inside (must be running)
docker exec lesson3 ls /usr/share/nginx/html
docker exec -it lesson3 sh
# exit leaves main process running

docker stop lesson3 && docker rm lesson3

Rules of thumb

inspect works on stopped containers; exec does not.
exec is a side process — not attach to PID 1; not restarted with the container.
Command must be an executable; use sh -c "…" for shell chains.
exit from exec shell ≠ docker stop.

From lesson 0003 · Sources: inspect, exec