The docker cp command serves for copying files and folders between Docker container and a host machine.
It is possible to copy a file or folder from host to container as well as from container to host.
In the examples below i am coping the files but the syntax for copying folders is the same. (more…)
The docker run command serves for creating containers from images.
In this article i will show how to run a Docker image as a container on the example of the official latest base image of Ubuntu.
I will show how to install apache2 inside a container with Ubuntu and how to save this container as a new image.
And finally i will show how to run this new Docker image as a container in the both interactive and background modes. (more…)
The docker pull command serves for downloading Docker images from a registry.
By default, the docker pull command pulls images from Docker Hub, but it is also possible to manually specify the private registry to pull from.
Before running the docker pull command it needs to search the Docker registry for the image to download.
In the examples below i will show how to pull the CentOS image from the official repository. (more…)
In the Docker’s world there are such concepts as images, containers and layers.
They are closely related, but distinct and at the beginning of studying Docker there is often a confusion in understanding of these concepts.
This article explains the differences between images, containers and layers. (more…)
All DNS records have a TTL (time to live) property that specifies the maximum amount of time the record may be cached.
In Linux you can make the DNS TTL lookup using the dig command.
You can both check the current domain remaining TTL as well as find out what TTL value is set on the name server where the domain is hosted on. (more…)
Normally, log rotation in Linux is handled by daily cron job.
The default configuration file is /etc/logrotate.conf and service or server specific configurations are stored in /etc/logrotate.d directory.
Sometimes it needs to force rotation of some files manually.
Below you will find how to debug and force logrotate manually. (more…)
By default, the docker ps command lists only running Docker containers.
With the specific options it is possible to list all Docker containers or filter output by the stopped containers only.
Below you will find how to check running Docker containers, how to list stopped Docker containers and how to list all Docker containers. (more…)
To delete a particular Docker image firstly you have to find out the IMAGE ID by listing the all local Docker images.
When the image for deletion is identified it can be removed with the docker rmi command.
From the command-line it is also possible to remove unused Docker images (not used by any containers) or, if it is needed, you can force removal of the all locally downloaded Docker images. (more…)
To delete a particular Docker container firstly you have to find out the CONTAINER ID or NAME by listing the all Docker containers.
When the container for deletion is identified it can be removed with the docker rm command.
From the command-line it is also possible to remove stopped (unused) Docker containers only or, if it is needed, you can force removal of the all Docker containers. (more…)
Sometimes it happens that you make some changes to a file but later realize that it was a mistake and these changes have to be discarded.
In Git you can revert the changes made to a file if you haven’t committed them yet, as well as you can revert a file to any previous commit.
Here i will show how to revert a single file to a specific revision and how to reset an uncommitted file to the initial master’s state. (more…)