Docker Basic Commands
Sets of commands for using Docker on CentOS linux distribution:
Note: it's recommended to run this commands as root
user or you should insert sudo
before each command.
You can check how to install Docker on CentOS
linux from Docker Documentation.
Start Docker platform on your local machine:
systemctl start docker
Check if Docker running properly on your local machine:
systemctl status docker
Create a container from hello world
image and start the container on your local machine:
docker run hello-world
If you get the message Hello from Docker!
then the container runs successfully.
Check the currently running containers on your local machine:
docker ps
You can add the option -a
to view the previously running containers on your machine:
docker ps -a
It will show detailed info about each container previously running:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 91582e45d7cc ubuntu "bash" 4 minutes ago Exited (0) 11 seconds ago agitated_pascal 949dcd991d2b hello-world "/hello" 49 minutes ago Exited (0) 49 minutes ago objective_dubinsky
As you see it gives you info about CONTAINER ID
, Image Name
and Instance Name
of the container.
Check container images on your machine:
docker images
It will show detailed info about each container image:
REPOSITORY TAG IMAGE ID CREATED SIZE ubuntu latest d2e4e1f51132 9 days ago 77.8MB hello-world latest feb5d9fea6a5 7 months ago 13.3kB
Get ubuntu
container image locally or pull it from Docker hub then create a new container from the image and start the container on your machine then enter the interactive bash remotely on the container:
docker run -it ubuntu bash
if you get root@2dff4fba5d4f:/#
then you are now on the running container bash.
you can run ls
to check the directories of the current ubuntu
container:
bin boot dev etc home lib lib32 lib64 libx32 media mnt opt proc root run sbin srv sys tmp usr var
To check home directory contents:
ls -asl home
We will create new folder on home
directory called lab
:
cd home
mkdir lab
We can check that lab
directory created on home
:
ls
Then we will create file on the lab
directory called container.txt
and we will write on it "ubuntu container instance"
:
cd lab
echo "ubuntu container instance" -> container.txt
Check if the file created by running command:
cat container.txt
It will output :
ubunto container instance
Now after we create the new directory and file on ubuntu
container we will exit from this container it will stop running directly:
exit
After exiting the container we can confirm that it stop running by:
docker ps
Then we will start ubuntu container another time:
docker run -it ubuntu bash
If we check the home directory now:
ls -asl home
We will not find lab
directory and the file we created previously because each time we run ubuntu
image we create new instance of the container.
we can check that by running:
docker ps -a
It will show these instances of ubuntu
container:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 91582e45d7cc ubuntu "bash" 4 minutes ago Exited (0) 11 seconds ago agitated_pascal bc56e9119461 ubuntu "bash" 20 minutes ago Exited (0) 7 minutes ago gracious_agnesi
To check the previous ubuntu
container instance which we created lab
directory on it:
First we start ubuntu
container instance we can find the name of the instance from the table gracious_agnesi
:
docker start gracious_agnesi
Then we enter the container instance bash using command:
docker attach gracious_agnesi
Now we can check the current container instance directory:
ls home -asl
It will show that the lab directory there then we check if the file container.txt
is there:
ls home/lab -asl
It will show file is still there, so as you see that each instance of ubuntu
container has its own state also it's separated from each other and that's one of the important features of containers technology.
Made with ❤ by Mohamad Oghli
I will update on this tutorial so check the GitHub repository.
Email:
mhd.sh.oghli@gmail.com