Docker commands in practice


Docker containers can be started, updated and managed using terminal commands. In the post I note commands that I have needed so far for Docker and corresponding examples:

Start container

A Docker container can be started with a simple "run" command:

 docker run -d \
   --name=testcontainer \
   -p=83:80 \
   --restart=always \
   -v mytestvol:/app \

The -p 83:80 parameter publishes port 83 and redirects it to port 80 in the container. Our just created container can be accessed in the browser using the IP address of the host and port 83:


A volume is a folder on the host operating system to permanently store data of the container. The -v parameter creates a volume and mounts it in the container.

   -v mytestvol:/app \

The location for the volume is managed by Docker by default and can be viewed with "docker inspect container name":

docker inspect testcontainer
        "Mounts": [
                "Type": "volume",
                "Name": "mytestvol",
                "Source": "/var/lib/docker/volumes/mytestvol/_data",

If you want to use a specific folder of the host operating system, you can also specify a path instead of the volume name (bind mount):

   -v /var/docker/mydockerfolder:/app \

":ro" at the end maps the folder read only

   -v /OrdnerNurLesend/:/OrdnerNurLesend:ro

See also: Docker data storage: Docker Volumes vs. Host Folders

Container parameters: Network

The parameter: --net=host connects the network card directly.

As an alternative the parameter

-p=external_port:port_in_container can be used:

-p=83:80 would then be able to be called via the IP of the computer with port 83 and internally in the container port 80 is used.

Additionally, with --network=network_name a specific network previously created with "docker network create" can be used. Containers within a network can be called not only by IP, but also by their name (--name): The name and port of the container are then simply used to establish the connection.

Show container

user@rechner:/docker$ docker ps
CONTAINER ID        IMAGE                                    COMMAND                  CREATED             STATUS                    PORTS                                      NAMES
????????????        syncthing/syncthing:latest               "/bin/ …"   12 minutes ago      Up 12 minutes (healthy)                                              festive_chandrasekhar
????????????        nginx                                    "/docker-entrypoint.…"   4 days ago          Up 12 minutes             80/tcp                                     nextcloud_webserver
????????????        nextcloud:fpm                            "/ php-…"   4 days ago          Up 12 minutes             9000/tcp                                   nextcloud_fpm
????????????        nginx                                    "/docker-entrypoint.…"   4 days ago          Up 12 minutes             80/tcp                                     laraveldev_webserver
????????????        mediawiki                                "docker-php-entrypoi…"   4 days ago          Up 12 minutes             80/tcp                                     mediawiki
????????????        laravelapp.dockerfile                    "docker-php-entrypoi…"   4 days ago          Up 12 minutes             9000/tcp                                   laravelapp
????????????        phpmyadmin/phpmyadmin                    "/docker-entrypoint.…"   4 days ago          Up 12 minutes   >80/tcp                       phpmyadmin
????????????        onlyoffice/documentserver                "/bin/sh -c /app/ds/…"   4 days ago          Up 12 minutes             80/tcp, 443/tcp                            onlyoffice
????????????        jrcs/letsencrypt-nginx-proxy-companion   "/bin/bash /app/entr…"   4 days ago          Up 12 minutes                                                        letsencrypt-companion
????????????        mariadb                                  "docker-entrypoint.s…"   4 days ago          Up 12 minutes             3306/tcp                                   mediawikidb
????????????        jwilder/nginx-proxy:alpine               "/app/docker-entrypo…"   4 days ago          Up 12 minutes   >80/tcp,>443/tcp   proxy
????????????        mariadb                                  "docker-entrypoint.s…"   4 days ago          Up 12 minutes             3306/tcp                                   db
????????????        mariadb                                  "docker-entrypoint.s…"   4 days ago          Up 12 minutes             3306/tcp                                   laraveldb
????????????        redis                                    "redis-server --appe…"   4 days ago          Up 12 minutes   >6379/tcp                     redis
????????????        laradock_nginx                           "/bin/bash /opt/star…"   3 months ago        Up 11 minutes   >80/tcp,>443/tcp   laradock_nginx_1
????????????        laradock_php-fpm                         "docker-php-entrypoi…"   3 months ago        Up 11 minutes             9000/tcp                                   laradock_php-fpm_1
????????????        laradock_phpmyadmin                      "/ supervisord…"   3 months ago        Up 12 minutes             9000/tcp,>80/tcp             laradock_phpmyadmin_1
????????????        laradock_workspace                       "/sbin/my_init"          3 months ago        Up 12 minutes   >22/tcp                       laradock_workspace_1
????????????        laradock_mariadb                         "docker-entrypoint.s…"   3 months ago        Up 12 minutes   >3306/tcp                     laradock_mariadb_1
????????????        laradock_redis                           "docker-entrypoint.s…"   3 months ago        Up 12 minutes   >6379/tcp                     laradock_redis_1

Stop container

docker stop containername

stop all containers

docker stop $(docker ps -a -q)

Update container

docker pull IMAGENAME
docker run CONTAINERNAME -parameters

Update Docker Compose Container

docker-compose pull
docker-compose up -d

Remove container

docker rm containername

Show network

user@rechner:/docker$ docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
????????????        docker_default      bridge              local
????????????        host                host                local
????????????        laradock_backend    bridge              local
????????????        laradock_default    bridge              local
????????????        laradock_frontend   bridge              local
????????????        nginx-proxy         bridge              local
????????????        none                null                local

Show detail of a network

docker network inspect docker_default

Calling the bash of a container

docker exec -it containername /bin/bash

Bash commands inside: mysql, mariadb DB restore

gunzip < '/daten/backup.gz' | docker exec -i laradock_mariadb_1 /usr/bin/mysql -u root --password=password dbname

Copy files from a container to the local file system.

docker cp graylog_graylog_1:/usr/share/graylog/data /var/web/graylog/data


Remove unneeded Docker images

docker image prune -a --force

Prune: delete unused data

docker system prune --volumes -f 

Monitor / Status

docker ps

docker ps lists all containers:

root@l2:~# docker ps
CONTAINER ID   IMAGE                    COMMAND     CREATED       STATUS       PORTS     NAMES
b345697c8b1b   portainer/agent:latest   "./agent"   3 hours ago   Up 3 hours             portainer_agent.l8lte8805fugp6xdc9sfizwbi.dru1imtp8l56zhby9863j9hi8


An overview of CPU / RAM and network is provided by the command docker stats

docker stats

Create image and transfer to a remote server

docker save image:latest | gzip > /var/web/image_web.tar.gz
scp /var/web/image_web.tar.gz root@remoteserver:/var/web/image_web.tar.gz

load on the remote server with:

docker load < /var/web/image_web.tar.gz

Show output of each container

docker logs -f containername


Docker stops responding

if, for example, commands like docker ps stop responding, the error can be narrowed down using the dockerd --debug command:

sudo dockerd --debug
INFO[2020-12-27T11:58:52.395359797+01:00] Starting up                                  
failed to start daemon: pid file found, ensure docker is not running or delete /var/run/

The file can be deleted with 

sudo rm /var/run/

failed to start daemon: error while opening volume store metadata database: timeout

I was able to fix Docker using the following commands:

Stop all Docker processes:

ps axf | grep docker | grep -v grep | awk '{print "kill -9 " $1}' | sudo sh

delete Metadata.db

sudo rm /var/lib/docker/volumes/metadata.db

Display the status

systemctl status docker

Reinstall Docker

sudo apt-get remove docker-ce
sudo apt-get install docker-ce
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