JavaEE: Install The Eclipse IDE On Windows

In this post we are going to install the Eclipse IDE for Java development.

Here are the steps to install Eclipse:

1. Go to https://eclipse.org/downloads click on the "Download 64-bit" button

Linux Administration: Disk Partitions Getting Partition Information With df And fdisk Commands

 As a Linux administrator there will be times when you go in blind and do not know why system you are logging into, one way to CSI your way through the system is with the fd and fdisk command.  Which will tell you who murdered Sideshow Bob.  Not really it will just tell you the systems disk information and the partition it has.  The first command you can run is the df command, if you run it by itself it would look a little cryptic.  So most of the time you will see people run it with the -h option

The df command which is an abbreviation of the words disk free is a command used to display the amount of available disk space for file systems.  It gives you amount of disk space available for each mount points.

The next command you can run is the fdisk command, as with df if you just type fdisk by itself, you won't get anything useful.  So you usually see it with the -l option

fdisk gives you the disk partition information as you can see we have two partitions and mount points, the first is a boot partition which does not have a lot of space which it does not need a lot of space.  The second partition has the bulk of space and is the system that we as users and administrators interact with.  It also tells you the swap size and mount points.  The home sector is also shown, you will often see the system administrator use this command when the system is running out of space.

SQL: Sort By Multiple Columns

SELECT UnitPrice, ProductName
FROM Products
ORDER BY UnitPrice DESC, ProductName

The query above sorts the results based on the most expensive products, and then the product name. Useful if you want a secondary sort criteria. For example if there are multiple products that are $14.00 then those products will be sorted by their names after the price has been sorted.

SQL: DATEPART Function

The DATEPART function extracts the date part of a date, for example using the 'yyyy' expression allows you to extract the year from a given date. The query below queries all the employees who were hired in the year 1994 in the Northwind Employees table.

SELECT FirstName + ' ' + LastName  AS Employee, HireDate
FROM Employees
WHERE DATEPART(yyyy,HireDate) = 1994

Iaas With AWS: VPC With Public And Private Subnets

 In most scenarios you don't want to expose all of your servers to be public facing.  You probably want to configure your network so that only the server that is hosting your web application is public facing.  What you want to do is put your web application on the public subnet and your backend servers on the private subnet.  This private subnet can access the internet through a NAT gateway for software updates and other functions that require internet access.  However, the outside world cannot establish a connection to servers in the private subnet.  The NAT gateway resides in the public subnet, acting as a bridge between the public subnet and private subnet.

JavaEE: Install Tomcat 9 On Windows

2. Under "Binary Distributions" select the last link

Linux Administration: Message Of The Day

As a Linux administrator you can set the message of the day for users to see when they are logged in.  It could be a reminder of a maintenance schedule or just to say high.  Or if you want to get fired a fake hacked message...j/k...lol  It does seemed like someone hacked your system sometimes when you see it as a user though.

The file that controls the Message of The Day message (pun) is located in /etc/motd 

All you have to do is modify the file to display the message to the users in your system.

So vi /etc/motd and type in your message and the next time a user logs in he will see the message

One caveat is that it will only appear in text terminal session login such as logging in using Putty you will not see the message if you log in using the GUI.

Unfortunately, you've been told that you've been hacked by Kanya's evil twin brother, who's a better rapper!

 

CSS HTML Attribute Selectors

In addition to class and ids you can also apply styles based on an element's attribute.  For example you can bold a href attribute that has the value "google.com" in it and match it exactly like this

    <style>
        a[href="https://www.google.com"]{font-weight: bold;font-size:200%;}
    </style>













As an  HTML creator you don't even need to worry about the markup, the selector automatically applies the styles once it finds the value.  So the markup would be like this

<a href="https://www.google.com">google.com</a>

SQL: AVG() Aggregate Function

The AVG() function gets the average of a column, the following query gets the average of the UnitPrice column in the Northwind Products table.

SELECT AVG(UnitPrice) AS AveragePrice
FROM Products

Iaas With AWS: Associate An Instance With AWS Elastic Network Interface

 In the previous post we associated our Elastic IP with an instance directly.  In this post we are going to take another approach to assign our Elastic IP to our instance.  In this approach we will create an Elastic Network Interface and associate it with our instance instead.  In the first approach the Elastic IP replaces the public IP because we associate it directly to the instance. But if we create an Elastic Network Interface we are essentially adding a second interface in our instance with two IPs, eth0 is the main network interface and eth1 will be the second interface.  It's like having two network interface in the physical world but this time it's virtualized in AWS.

Here are the steps to create a network interface:

1. Create an Elastic IP, follow this post if you don't know how.

If you look at the instance description you will see that there's no Elastic IP address assignment, so if you stop and start the instance you will get a new public IP, and there's only one network interface (eth0). By the time we are finish with this post the instance will have tow network interfaces and an Elastic IP.