docker run, ps, start/stop/restart, exec, logs, rm, flags, restart policies.

docker run basics

docker run = pull (if needed) + create + start. By default attached to terminal; -d detaches.

• Foreground: docker run nginx

• Detached + named: docker run -d --name web nginx

• One-off, auto-remove: docker run --rm alpine echo "hello"

• Interactive shell: docker run --rm -it alpine sh

• Override CMD: docker run --rm alpine cat /etc/os-release

Args after image name replace image’s default CMD. ENTRYPOINT (if any) still runs.

Common flags

Restart policies

Recommended for services: --restart unless-stopped.

List

• Running: docker ps

• All: docker ps -a

• IDs only: docker ps -aq

• Filter: docker ps --filter "status=exited" docker ps --filter "name=web"

• Custom format: docker ps --format "table {{.Names}}\t{{.Status}}\t{{.Ports}}"

• Disk usage: docker ps -s

Inspect

• Full JSON: docker inspect web

• Specific field: docker inspect --format '{{.State.Status}}' web docker inspect --format '{{.NetworkSettings.IPAddress}}' web

• Live resource stats (one-shot): docker stats --no-stream

• Processes inside: docker top web

Logs

• Dump: docker logs web

• Follow: docker logs -f web

• Last N with timestamps: docker logs --tail=100 -t web

• Recent: docker logs --since=10m web

• Range: docker logs --since=2024-01-01T00:00:00 --until=2024-01-02T00:00:00 web

docker logs requires json-file or journald log driver. Cap log size in daemon.json or with --log-opt max-size=10m.

Exec

• Interactive shell: docker exec -it web sh docker exec -it web bash # if image has bash

• One command: docker exec web cat /etc/nginx/nginx.conf

• As different user: docker exec -u root -it web sh

• Working dir + env: docker exec -w /var/log -e DEBUG=1 web ls -la

exec only works on running containers; start first if stopped.

Start / stop / restart / pause

• Graceful stop (SIGTERM then SIGKILL after 10s): docker stop web

• Custom grace: docker stop -t 30 web

• Start stopped: docker start web

• Restart: docker restart web

• Pause / unpause (cgroup freeze): docker pause web / docker unpause web

• SIGKILL: docker kill web

• Custom signal: docker kill --signal=SIGHUP web

Remove

• Stopped: docker rm web

• Force (stops + removes): docker rm -f web

• All stopped: docker container prune

Copy files

• Container → host: docker cp web:/etc/nginx/nginx.conf ./nginx.conf

• Host → container: docker cp ./newconfig.conf web:/etc/nginx/nginx.conf

• Whole dir: docker cp web:/var/log/nginx ./nginx-logs

Practical examples

Postgres for dev (persistent)

docker run -d \
  --name pg \
  --restart unless-stopped \
  -p 5432:5432 \
  -e POSTGRES_USER=dev \
  -e POSTGRES_PASSWORD=dev \
  -e POSTGRES_DB=devdb \
  -v pgdata:/var/lib/postgresql/data \
  postgres:16

docker exec -it pg psql -U dev -d devdb

Redis

docker run -d \
  --name redis \
  --restart unless-stopped \
  -p 6379:6379 \
  redis:7-alpine

docker exec -it redis redis-cli

Shell sandbox

docker run --rm -it alpine sh
docker run --rm -it debian:bookworm-slim bash

Bind-mounted nginx with hot config reload

docker run -d \
  --name web \
  --restart unless-stopped \
  -p 80:80 \
  -v "$(pwd)/nginx.conf:/etc/nginx/nginx.conf:ro" \
  -v "$(pwd)/site:/usr/share/nginx/html:ro" \
  nginx:1.27

docker exec web nginx -s reload

Throwaway build environment

docker run --rm \
  -v "$(pwd)":/src \
  -w /src \
  golang:1.22 \
  go build -o myapp ./cmd/myapp

Quick reference