In this post, we will see the top 17 important docker commands that we generally use in Docker environment.
These are the basic Docker commands you need to get started with Docker containers and images.
Install Docker
Before going ahead, take a look at how to install Docker on famous Linux distributions.
READ: How To Install Docker on CentOS 7 / RHEL 7
READ: How To Install Docker on Ubuntu 18.04
READ: How To Install Docker on Ubuntu 16.04
READ: How To Install Docker on Debian 10
READ: How To Install Docker on Debian 9
READ: How To Install Docker on Fedora
Top 10 Docker Commands
Find Docker Version
Let’s check the Docker version installed on the machine.
docker -v
Output:
Docker version 19.03.1, build 74b1e89
You can also use version command to know about Docker components and versions.
docker version
Output:
Client: Docker Engine - Community Version: 19.03.1 API version: 1.40 Go version: go1.12.5 Git commit: 74b1e89 Built: Thu Jul 25 21:21:07 2019 OS/Arch: linux/amd64 Experimental: false Server: Docker Engine - Community Engine: Version: 19.03.1 API version: 1.40 (minimum version 1.12) Go version: go1.12.5 Git commit: 74b1e89 Built: Thu Jul 25 21:19:36 2019 OS/Arch: linux/amd64 Experimental: false containerd: Version: 1.2.6 GitCommit: 894b81a4b802e4eb2a91d1ce216b8817763c29fb runc: Version: 1.0.0-rc8 GitCommit: 425e105d5a03fabd737a126ad93d62a9eeede87f docker-init: Version: 0.18.0 GitCommit: fec3683
The info command prints how many containers and images are there along with the information about the operating system, kernel version, CPU, Memory, and hostname.
docker info
Output:
Client: Debug Mode: false Server: Containers: 0 Running: 0 Paused: 0 Stopped: 0 Images: 0 Server Version: 19.03.1 Storage Driver: overlay2 Backing Filesystem: xfs Supports d_type: true Native Overlay Diff: true Logging Driver: json-file Cgroup Driver: cgroupfs Plugins: Volume: local Network: bridge host ipvlan macvlan null overlay Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog Swarm: inactive Runtimes: runc Default Runtime: runc Init Binary: docker-init containerd version: 894b81a4b802e4eb2a91d1ce216b8817763c29fb runc version: 425e105d5a03fabd737a126ad93d62a9eeede87f init version: fec3683 Security Options: seccomp Profile: default Kernel Version: 3.10.0-957.21.3.el7.x86_64 Operating System: CentOS Linux 7 (Core) OSType: linux Architecture: x86_64 CPUs: 1 Total Memory: 1.655GiB Name: centos ID: RZCG:TOSQ:RL7B:A7FF:ASDB:47GR:KN24:BRKF:KYHZ:5WVV:UTOZ:CDSX Docker Root Dir: /var/lib/docker Debug Mode: false Registry: https://index.docker.io/v1/ Labels: Experimental: false Insecure Registries: 127.0.0.0/8 Live Restore Enabled: false
Docker Containers
Create a Docker Container
Though there is a separate command only to create containers, the following command is widely used to create and run containers. It uses the fedora latest docker image to create and start a container.
docker run -dit --name docker-fedora --hostname="fedora" fedora /bin/bash
-d: Run a container in background and print container ID
-i: Run a docker container in interactive mode
-t: Allocates tty terminal which is required to attach to the container
–name: Name of the docker container
–hostname: Set a host to the container
When you issue the command, Docker looks for Fedora image locally, and if it is not found, it will start downloading the Fedora image from Docker registry. Once the image has been downloaded, it will start the container.
Unable to find image 'fedora:latest' locally latest: Pulling from library/fedora fd2e8b5b2254: Pull complete Digest: sha256:d39a02a0f13c1df3bbcb0ccea4021c53b8e0bfd87f701a5115e18ec089814e70 Status: Downloaded newer image for fedora:latest 8bba0f0ffe3a4553212da5c1bbdca0fac35a210c780f92d0df15fba0feec0a60
List Docker Containers
Check the running containers using the below command.
docker ps
OR
docker container list
Output:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 8bba0f0ffe3a fedora "/bin/bash" About a minute ago Up About a minute docker-fedora
Access Docker Container
The attach command lets you access the running container (docker-fedora). You can see that the container hostname is set to Fedora. Also, run some test commands like “df -hT” to see the mount points details.
docker attach docker-fedora
OR
docker container attach docker-fedora
Output:
[[email protected] ~]# docker attach docker-fedora [[email protected] /]# df -hT Filesystem Type Size Used Avail Use% Mounted on overlay overlay 10G 2.6G 7.5G 26% / tmpfs tmpfs 64M 0 64M 0% /dev tmpfs tmpfs 848M 0 848M 0% /sys/fs/cgroup shm tmpfs 64M 0 64M 0% /dev/shm /dev/sda1 xfs 10G 2.6G 7.5G 26% /etc/hosts tmpfs tmpfs 848M 0 848M 0% /proc/acpi tmpfs tmpfs 848M 0 848M 0% /proc/scsi tmpfs tmpfs 848M 0 848M 0% /sys/firmware
Check Running Process in Container
The top command shows the running process and its details.
docker top docker-fedora
OR
docker container top docker-fedora
Output:
UID PID PPID C STIME TTY TIME CMD root 3724 3708 0 07:51 pts/0 00:00:00 /bin/bash
Check Docker Container Statistics
The stats command does live stream of container’s resource usage statistics. The output stats will be similar to Linux’s top command.
docker stats docker-fedora
OR
docker container stats docker-fedora
Output:
CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS 8bba0f0ffe3a docker-fedora 0.00% 620KiB / 1.655GiB 0.04% 656B / 0B 0B / 0B 1
Copy file/folder from Docker Container
The cp command will allow you to copy files/folders from containers to a host system. The following command will copy /root/tobecopied file to /root of a host machine.
docker cp docker-fedora:/root/tobecopied /root/
OR
docker container cp docker-fedora:/root/tobecopied /root/
Stop Docker Container
The kill command sends the SIGTERM signal to kill a running container.
docker kill docker-fedora
OR
docker container kill docker-fedora
You can use docker ps -a command to see the container status.
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 8bba0f0ffe3a fedora "/bin/bash" 11 minutes ago Exited (137) 5 seconds ago docker-fedora
Start Docker Container
The start command allows you to start a stopped container.
docker start docker-fedora
OR
docker container start docker-fedora
Restart Docker Container
The restart command allows you to restart a container.
docker restart docker-fedora
OR
docker container restart docker-fedora
Stop Docker Container
The stop command helps you stop a container gracefully
docker stop docker-fedora
OR
docker container stop docker-fedora
Rename Docker Container
The rename command provides an ability to change the name of the container, following command rename the docker-fedora to MyFedora.
docker rename docker-fedora MyFedora
OR
docker container rename docker-fedora MyFedora
Remove Docker Container
The rm command helps you to remove a container. If the container is running, use -f to force remove it.
docker rm MyFedora
OR
docker container rm MyFedora
Docker Images
Search Docker Images
The search command helps you to search for Docker images in the Docker registry, lets search images related to WordPress.
docker search wordpress
Output:
NAME DESCRIPTION STARS OFFICIAL AUTOMATED wordpress The WordPress rich content management system… 3066 [OK] bitnami/wordpress Bitnami Docker Image for WordPress 115 [OK] tutum/wordpress Out-of-the-box WordPress docker image 35 appcontainers/wordpress Centos/Debian Based Customizable WordPress C… 34 [OK] aveltens/wordpress-backup Easily backup and restore your WordPress blo… 16 [OK] centurylink/wordpress WordPress image with MySQL removed. 14 [OK] arm32v7/wordpress The WordPress rich content management system… 10 appsvcorg/wordpress-alpine-php This is a WordPress Docker image which can … 7 dalareo/wordpress-ldap WordPress images with LDAP support automatic… 6 [OK] bitnami/wordpress-nginx Bitnami Docker Image for WordPress with NGINX 6 [OK] wodby/wordpress-php PHP for WordPress 4 [OK]
Pull Docker Images
The pull command allows you to download Docker images from the registry. By default, it downloads from Docker public registry. But, you can also set Docker to download images from your private registry.
docker pull wordpress
OR
docker image pull bitnami/wordpress
Push Docker Containers
Here is the tutorial on how to push your Docker images to Docker Hub.
List Docker Images
List the available Docker images on the system.
docker images
OR
docker image list
Output:
REPOSITORY TAG IMAGE ID CREATED SIZE bitnami/wordpress latest da1f627a8dfd 2 days ago 417MB wordpress latest 02126202b6ea 6 days ago 502MB fedora latest ef49352c9c21 10 days ago 246MB centos latest 9f38484d220f 5 months ago 202MB fedora 29 d09302f77cfc 5 months ago 275MB
Remove Docker Images
You can remove downloaded images using rmi or rm command
docker rmi wordpress
OR
docker image rm wordpress
Output:
Untagged: wordpress:latest Untagged: [email protected]:fdecb6fc92b04d88419544722ac1679158c12eb8f519b83b0480a6375e823dec Deleted: sha256:02126202b6ea3d070a0d2e9ded8ea7cc94073525fba5839204fed4f6de62a527 Deleted: sha256:006265425edfa4451bb0b69607ca56bf05576c5ee7dbfd5abe4382ab67175537 Deleted: sha256:fba7a866c3b6a68aacb937015533cc65fa563988e9b58258ff82c48554cfc609 Deleted: sha256:a8222cc6dc755223abf4af699ae1090020858fcaffd431b32a116c9c1cc0609d Deleted: sha256:a310023bf66eb8e4118deafdf12c800a98d9a77932906d141839bad1963dd96b Deleted: sha256:87b8b6fb7a45af0d8c4aec69d808a8d43c0e177e89284289f6a02da4aaa617a7 Deleted: sha256:119f74a6f3f65b1a989e6015579e6ada9916ac20128699bc63c20cf71b5fd8db Deleted: sha256:8976d948286158c42b155e2ba9a9039a23005db8b67ca5471abaac20d54b7dd4
You can also remove all images in a single go which would save you lots of time.
Conclusion
That’s All. I hope you are now able to work with Docker containers and images.
