You know how to pull and create custom images; do whatever with them.
But if you need the same custom image on multiple servers in your network, you will have to copy that image on them. Here comes docker registry: a local repository of your images.
And the installation of a local repository is done via (guess?) a container :).
Basically, all you have to do is to pull the registry image and run a container on top of it. As simple as that!

So I finally got a bit into docker because everybody is talking about it.
I will skip the installation part because it is not that difficult (easier than windows install actually: next, next, finish) and go straight to the interesting part: using docker commands.

Got the following error when attempting to upgrade outdated via port upgrade outdated:

Almost all operating system have command line commands. They are always there, even if we do not know about them.
Actually, the GUI programs that provide us ways to do things, like Disk Util for example, are just a graphical wrap over the command line tool. And they do not provide all the features.

Today, I will show you how to update your MacOS via command line. Benefits: you only need to restart once and the first phase of the installation can be done while you do your stuff so no need to wait for the progress bar to fill up and then reboot.

You have upgraded to macOS High Sierra and found this error while trying to upgrade macports via command line?

fmbp:~ florian$ sudo port -v selfupdate
Error: Current platform "darwin 17" does not match expected platform "darwin 16"
Error: If you upgraded your OS, please follow the migration instructions: https://trac.macports.org/wiki/Migration
OS platform mismatch
    while executing
"mportinit ui_options global_options global_variations"

The servers setup:

To install the required packages run on both servers:

$ sudo apt-get install glusterfs-server

You have upgraded to macOS Sierra and found this error while trying to upgrade macports via command line?

fmbp:~ root# port -v selfupdate
Error: Current platform "darwin 16" does not match expected platform "darwin 15"
Error: If you upgraded your OS, please follow the migration instructions: https://trac.macports.org/wiki/Migration
OS platform mismatch
    while executing
"mportinit ui_options global_options global_variations"
Error: /opt/local/bin/port: Failed to initialize MacPorts, OS platform mismatch

Every file is a hard link. It is a label or name assigned to a set of information which resides on the hard disk. In most of the cases there is a single name assigned to a file (a single hard link).
I it possible however to create different names which all refer to the same content.
Why you would do that? There are various reasons.
Some quick examples:
- backups that keep various versions of your data can use hard links for files with the content unchanged.

Create RAID 1 with missing volume (will destroy the data on the volume):

[osx@mini Volumes]$ diskutil appleRaid create mirror vbox JHFS+ disk2s2
Started RAID operation
Unmounting proposed new member disk2s2
Adding a booter for the RAID partition disk2s2
Creating a RAID set
Bringing the RAID partitions online
Waiting for the new RAID to spin up "2134725A-668E-45C3-BBD6-AAD5FF4D1991"
Initialized /dev/rdisk10 as a 477 GB case-insensitive HFS Plus volume with a 40960k journal
Mounting disk

There are several applications, including monitoring solutions, which are able to interpret a json or any other type of message if sent correctly and according to each application's rules.

The way to do this is limitless but I will present you below only 2 methods. They have as example a json message.

With curl

Curl is able to send any message you want and json is not exception. The only thing is some application require certains http headers and others must not get anything but the message.