Friday Fun: Improved PowerShell Napping

So I had some fun with my post last week on taking a nap with PowerShell. I got some great feedback on Twitter and a new comments on the blog. My initial effort was a relatively simple PowerShell script which certainly got the job done. But I there were a number of areas where I could expand and improve the script and they would be terrific teaching aids. So I did.

The function is defined in a script you can find in Github.

Let’s look at some of the changes I made. First off, I turned this into a function complete with comment based help. You’ll need to dot source the script file into your PowerShell session or profile script to make the command available.

I made just about every option a parameter and added a few parameter aliases as well. So even though I made the Minutes parameter positional so that you don’t need to use the parameter name, you could use –Nap or –Time. You’ll notice I also made the wakeup message a parameter.  Feel free to set your own default value. Otherwise, you can set a different message at different times.

I also realized that if you are napping, someone might still drop by your desk. So I included an option to display a progress bar using Write-Progress. This is a cmdlet that doesn’t get the love it should.

I defined an array of messages:

The messages will be used as the Status property for Write-Progress. I like using a hashtable of parameters to splat when using Write-Progress.

If I use the Progress bar, it is displayed using the seconds remaining.

And every 10 seconds I set the status to another randomly selected message. The result is something like this:

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The last major change I made per a suggestion was to use the text to speech feature to have a Windows voice “say” the wake up message. I added a parameter for you to specify a voice name which in the US will most likely be David or Zira.  If you don’t know the names, you can specify a bogus value like ‘foo’ and the function will display the available names. This works because I added a validation script to the Voice parameter.

This is probably a bit more involved than most validation scripts.  The main takeaway is that if you use a validation script it has to return either True or False, or throw an exception as I’m doing here. But it works.

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By adding a voice option I decided the function could either display the message using Write-Host or speak it. The chime happens in either event.

What this meant was that I had to differentiate the parameters which I did with parameter sets.  I specified the default in the cmdletbinding attribute.

Then I needed to specify a parameter set name for each parameter.  If you don’t specify parameter set name, then the parameter will belong to all sets.  Or you can do as I did and be explicit. If you do it properly it should be reflected in the help.

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You can see that there are 2 ways to use this command. I’ll let you grab a copy and try out the new additions.

Certainly this isn’t a production oriented script but I hope it serves up some interesting examples of different scripting techniques and cmdlets.

As always, comments sincerely welcomed.

Enjoy!

Friday Fun: A PowerShell Nap

antique-watch-150x225I’m hoping that I’m not the only one who feels their butt dragging by mid to late afternoon. Let’s say that’s because we’ve been thundering through the day and by 3:00 we’re a bit out of gas. Yeah, I’ll go with that.

I find myself wanting to close my eyes for only a few minutes to recharge and or at least take the tired edge off.  In other words, I just want a quick nap like we had in kindergarten.  But I need to make sure I wake up! Since I always have a PowerShell console, I can use it as a quick and dirty alarm clock.

For starters I can use the Start-Sleep cmdlet to wait for X number of seconds. So if I want say a 10 minute timer I can run:

But if my eyes are closed how will know when time is up? A quick solution is to make my computer beep using the [console] .NET class.

So to run this all at once I can enter a command like this:

The semi-colon is the end of command marker so what I’m really doing here is executing 2 commands. PowerShell will sleep for 600 seconds and when that command completes, then the Beep() method will run.

But of course it is Friday so let’s have a bit more fun with this.

The Beep() method can also take 2 parameters. The first is a tone frequency, and the second is a duration in milliseconds.

With this in mind I put together a PowerShell napping script.

The script takes a parameter for the number of minutes you need to nap. It then writes a message to anyone who might be walking by your desk to keep quiet.  The script then does a countdown of sorts by calculating a timespan between the target end time and the current time. I’m writing the value as a string so that I can strip off the milliseconds.

nap in progress

nap in progress

At the end of the countdown I’ve recreated a well known chime, at least for those of you in the United States and of a certain age. I’ll let you try it out for yourself.

nap complete

nap complete

So get a bit more work done today,  and when you’re ready, take a quick PowerShell Power nap.

Enjoy and sweet dreams.

Friday Fun: Number Crunching

Earlier this week I was looking at the GoFundMe website in the midst of debating a new project. One of the considerations I have for sites like this is the expense involved. Certainly I don’t expect this type of service to be free. But I started wondering about what net donations might look like. According to GoFundMe, assuming I am interpreting this correctly, the site takes 5% of the donation right off the top. In addition to that there is a processing fee of 2.9% of the donation plus 30 cents. At least for the US. So for a $10 donation the net donation would be $8.91.

10 – (10*.05) – (10*.029 +.30)

Alright then.  This should be simple enough to turn into a PowerShell function.

This also should make for a fun learning opportunity.

The function takes a parameter for the donation amount. I cast it as a [double] in the event someone might donate $10.25. If used [int] PowerShell would turn it into $10.  I’ll come back to the other parameter in a bit.

I define the rates from GoFundMe as variables.  This makes it easier to calculate some values.

You’ll note that I’m using the Round() method of the .NET Math class. This is so that the result is formatted to 2 decimal points.  This is what I want to see, not necessarily how the site operates. With these values I can create a custom object.

Here’s a simple demonstration, and yes I know I’m not using a standard function name but this is for fun.

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I also wrote the function as an advanced function so that I can pipe values into it. If you look at the parameter definition for $Donation you’ll see that I have a setting for ValueFromPipeline.

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This makes it pretty clear about what happens with each donation.  But what did I end up with?  My function writes objects to the pipeline so that I can use other cmdlets, like Measure-Object.

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Here’s the fun part: I can measure multiple properties.

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I thought that was pretty handy.

I know that the values are in dollars.  But let’s say I was creating a report and I wanted to make it pretty and include the $ sign, or whatever my currency symbol might be.

If you recall, I included a switch parameter called UseCurrency along with a parameter alias of currency.

If I run the function with –UseCurrency, then this parameter will have a value of $True. That is how a Switch parameter works. In my function I can test the parameter value and it it is true, then I’ll create the same custom object, except that I will use the –F operator to format the value as a string using the currency symbol.

This operator is used to format strings in the .NET Framework. You can read more about this online at http://go.microsoft.com/fwlink/?LinkID=166450. But in short, the {0} on the left side of the operator is a numbered place holder. The c is the modifier which in this case indicates to use a currency format string and I’m limiting it to 2 places.  I probably don’t need that since I’m already rounding but I left it in for the sake of education.  On the right side of the –f operator is a comma separated list of values that will “plug in” to the place holders. The net result is this:

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That looks pretty, but be aware that these values are strings.

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This means my previous method of getting a sum will fail.  Instead I need to use numbers and then format the result.

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Now I have the best of everything. Although if I truly want to make a pretty report, I can use Format-Table so that I can specify an alignment on the custom property.

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I hope you found this fun and informative.  If you have any questions about what I did or why, please drop them in the comments.

Friday Fun Learning from Spam

Today’s article is definitely on the amusing side, although hopefully it will make for an interesting learning opportunity. Earlier this week I was clearing out spam on my blog and found a comment that looked like the spammer’s template file. The comment contained a number of short entries like this:

Sample spam templateSample spam template (Image Credit: Jeff Hicks)

The poor English aside, I thought it was kind of funny. First off, it is clear that whatever code he (making an assumption, sorry) was using failed to properly run. Then I thought that I could use this text and do the same thing in PowerShell. It is pretty clear to me that to create a proper spam comment, I need to select a choice from each option enclosed in curly braces. So let’s do that. Let’s build some spam with PowerShell. I’ll use the text file from above.

The trickiest part, at least for me, was coming up with a regular expression pattern to select everything in the curly braces. Eventually I came up with this:

To start with, I’ll test with a single line of text.

Which gives me these matches:

My spam matches
My spam matches (Image Credit: Jeff Hicks)

I’ll focus on the first match. I don’t need the {} characters so I can replace them with empty strings and then split what remains on the | character.

This gives me an array of choices which I can select with Get-Random.

With this, I can use the replace method to replace the matching value that is, the text with the curly braces, with my randomly selected choice.

Inserting the replacementInserting the replacement (Image Credit: Jeff Hicks)

I can repeat this process for the other values. Here’s how I might do this for a single line:

The complete line
The complete line (Image Credit: Jeff Hicks)

I never promised elegant poetry.

Now that I have the technique, I can apply it to the entire file looping through each line.

And here is the glorious, delicious spammy result:

PowerShell generated spam!PowerShell generated spam! (Image Credit: Jeff Hicks)

Yes, this is absolutely silly and borderline ridiculous. But this serves as a nice tool for learning about regular expressions, replacements and splitting. If you want some spam samples to play with you can download a zip file here.

Have a great weekend.

Friday Fun: Holiday Shopping with PowerShell

Once again, the holiday shopping season is upon us. But perhaps PowerShell can make it a little easier or at least a bit more fun. I’m sure many of you have shopped at NewEgg.com. Perhaps you plan to do so again this year for friends, family or even yourself. So why not let PowerShell make this a bit easier.

NewEgg is savvy enough to publish RSS feeds for a number of their sales categories. You can find a master list at http://www.newegg.com/RSS/Index.aspx.  Let’s take their Deal of the Day feed.

Using Invoke-RestMethod, it is very easy to retrieve items.

But it is still a bit of a jumble, so let’s get a bit more selective.

I also created a new property called Published which takes the original PubDate and treats it as a date which makes the data easier to sort or filter.

Here’s a sample of what I retrieved.

A NewEgg Deal of Day itemA NewEgg Deal of Day item (Image Credit: Jeff Hicks)

With this data, I can use Out-Gridview as an object-picker.

Links in Out-GridviewLinks in Out-Gridview (Image Credit: Jeff Hicks)

I can select multiple entries, click OK and each link should open up in my browser.

The online dealThe online deal (Image Credit: Jeff Hicks)

But let’s make things a bit more interesting. The Title property includes the price and description. I have no idea what these links look like in other parts of the world so you may have to adjust the following examples.

First, I’m going to define a regular expression pattern to use named captures to get the currency, in my case $, the price and the item description.

I’m going to re-download the data skipping any entry that doesn’t have what looks like a price in the title field.

My goal is to use Out-Gridview again with separate properties for the currency and price. I need the price to be numeric so that I can sort on it. I next get the currency symbol using the regex expression.

Then I can process the rest of the RSS data, using the regex object to parse out the price and description.

If you notice, I used the Currency value as a property name. Now when I use Out-Gridview I have a more flexible display.

Reformatted DealsReformatted Deals (Image Credit: Jeff Hicks)

If I’m shopping for a new laptop, I can select multiple entries, click OK and review them in my browser.

Viewing my choicesViewing my choices (Image Credit: Jeff Hicks)

I can repeat the process by changing the RSS feed, say to their Shell Shocker

If I repeat the previous steps, this will fail, which brings up something to keep in mind with regular expressions: know your data. You have to know what you are processing and that it follows a predictable pattern. At least if you want to keep your regular expression patterns relatively simple. The problem here is that there is only a single item. So my code to get the currency figure fails, because I don’t have an array. In this situation I could do this:

Although it might make more sense to come up with code that I can re-use.

But from here the code is the same.

Shell Shocker itemShell Shocker item (Image Credit: Jeff Hicks)

That might be something I want to look into, although sometimes the RSS feeds are bit behind the site. Sadly, in this case, the link works, but the product is something else. But you get the idea.

Enjoy your holiday weekend and be careful out there!