Category Archives: PowerShell

Friday Fun: Another Christmas Prompt

christmastree In last week’s Friday Fun post, I shared with you a PowerShell prompt that would display a festive Christmas countdown clock. This week I have another holiday related prompt function. This one is pretty straight forward and is not that much different from the default PowerShell prompt function.

I included some logic so that my customization only happens during the month of December and before Christmas. The prompt changes the background color of your console between DarkRed and DarkGreen. The first time you run it, the prompt will randomly select a color. You might want to run Clear-Host, or CLS after loading the prompt.

After that the background color will toggle leaving you with an effect like this:

christmasprompt2014-redgreen

It is interesting to see how different commands write to the console. You could even combine both of my prompts if you are in an especially festive mood.

christmasprompt2014-everything

There’s probably no practical value in this other than having some fun and maybe understanding some PowerShell scripting concepts. Hope your holiday shopping is going well. Have a great weekend.

Friday Fun Christmas Countdown Prompt

christmaslights It’s that time of year again where PowerShell can make all your wishes come true. Ok, maybe that’s a bit much, but PowerShell is the gift that keeps giving all year long. Again, maybe too much. How about this? Here’s a revised version of my Christmas countdown prompt. I’ve posted this in the past. But some of you are new to PowerShell and may have missed it. Plus I’ve revised it a bit.

In PowerShell you have a built-in function called Prompt. It controls what you see in the console which is usually something like PS C:\>. But you can create your own Prompt function. Here’s my Christmas countdown prompt.

I’ve inserted plenty of comments so you should be able to understand how it works. In a nutshell, the prompt inserts a message that indicates how much time remains before December 25th of the current year. The text also includes some special characters to help embellish it and put you in the holiday mood. Finally, each character is written to the host with a random color. You can see that I used a Switch construct to evaluate the random number with an expression.

This function will work best in the PowerShell console. If you want to try it out you can copy and paste this function into your console session. Your PowerShell session will now look like this:

christmasprompt2014

The prompt will only last for as long as your PowerShell session is running. The next time you start PowerShell you will be back to your original prompt. If you enjoy this, put my Christmas prompt function in your PowerShell profile, but be sure it is called Prompt. When the holidays are over simply comment out the function. Or you could add some logic to your profile.

Ho-Ho-Ho! Have a great weekend.

Friday Fun: I’m with the band.

black-guitarI like to have fun with PowerShell, as is hopefully evident with this Friday Fun serious, and today that is especially true. Perhaps you need a quick break from the end of the week grind. Or maybe you want to learn something new about PowerShell. Hopefully today’s fun will meet both requirements. Today’s fun will include XML, scope and Switch. Let’s rock.

If you haven’t figured it out, rock ‘n roll is the theme for today. I have put together a little rock and roll quiz. In many rock bands there’s at least one member is well known. If someone says “Axl Rose” you most likely will know Guns n’ Roses. But would you recognize the other members of the band? I created an XML document with a number of well known rock bands. Because band members change, I tried to use the line ups from the bands peak years. If you want to play you will need to download BandData.xml. Save as an XML file to same directory as the script, which I’ll show you in a moment. Try not to peek too much at the contents. This is the structure.

My quiz is a PowerShell script that processes the data in the XML document. It will display a list of band members, without the recognizable lead and multiple choice of possible bands. After answering the questions you will be judged, I mean graded.

Let’s look at a few key points of the script.

First, I need to load the XML document.

The [XML] type accelerator will create an XML document. When you have an XML document in PowerShell, each node can be treated like a property so it is very easy to navigate or get values, like a list of all the band names.

The script then selects a random number of band entries from the XML document. These will be the basis of the quiz. For each item I create a list of band choices and band members that will be displayed. You’ll also noticed that I initialize some counters with the $script prefix.

Here’s why. I am using a scriptblock, defined as $promptblock, to display each question and keep track of correct answers. The scriptblock runs in a new scope, or container. That means when it tries to do something with a variable like $Q it first looks in the current scope for that item. If it finds it, it uses it. Otherwise PowerShell searches up the scope hierarchy to the parent scope looking for the item. But here’s what trips people up. If you are only reading, like I am, for things like the $bandhash object, PowerShell will happily find it in the parent scope and display it. But when I try to modify a variable like $Q or $i it can only modify it in the current scope. But I need to use those variables outside of the scriptblock scope, so I preface the variable with $Script: to indicate the scope level for those variables. The general rule is to not reference out-of-scope variables, but since I’m using $script: I’m telling PowerShell I know what I’m doing.

After running through all the questions, the script can calculate how many correct answers you had and present a score card. I decided to use a Switch statement to assist.

Normally in a Switch you would use a simple value. But you can also use PowerShell expressions. In my Switch statement, if the value of $Correct is >= 90, then I assign a certain value to $quip. When using expressions, use $_. Remember that Switch will process every matching expression and since I don’t want that, I’m using the Break keyword so PowerShell knows not to keep checking the other possibilities.

When you run the quiz, you will get an item like this:
bandquiz-1

The display is from the prompt scriptblock. If you need a little help, enter 0 which re-displays the question this time with the (hopefully) more recognizable lead.

bandquiz-2

And the final snarky commentary on your rock knowledge.
bandquiz-3

Because I am of a certain age, the contents of my band data xml file might be slightly skewed. If you were born after 1985 you might have some problems.

I think XML files scare some IT Pros but they really aren’t that difficult to work with once you understand some basics. In fact, I’ll be coming back to my band xml file in future posts. In the mean time, party on and let me know if you have any questions about my quiz script.