File Age Groupings with PowerShell

I’m always talking about how much the object-nature of PowerShell makes all the difference in the world. Today, I have another example. Let’s say you want to analyze a directory, perhaps a shared group folder for a department. And you want to identify files that haven’t been modified in a while. I like this topic because it is real world and offers a good framework for demonstrating PowerShell techniques.

You would like to divide the files into aging “buckets”. Let’s begin by getting all of the files. I’m using PowerShell 3.0 so you’ll have to adjust parameters if you are using 2.0. You can run all of this interactively in the console, but I think you’ll find using a script much easier.

Now, let’s add a new property, or member, to the file object called FileAgeDays which will be the value of the number of days since the file was last modified, based on the LastWriteTime property. We’ll use the Add-Member cmdlet to define this property.

The new property is technically a ScriptProperty so that we can run a scriptblock to define the value. In this case we’re subtracting the LastwriteTime value of the each object from the current date and time. This will return a TimeStamp object but all we need is the TotalDays property which is cast as an integer, effectively rounding the value. In a pipelined expression like Select-Object you would use $_ to indicate the current object in the pipeline. Here, we can use $this.

Next, we’ll add another script property to define our “bucket” property.

The script block can be as long as you need it to be. Here, we’re using an If/ElseIf construct based on the FileAgeDays property we just created. If we look at $files now, we won’t see these new properties.

fileage-01

But that is because the new properties aren’t part of the default display settings. So we need to specify them.

fileage-02

Now, we can group the objects based on these new properties.

fileage-03Or perhaps we’d like to drill down a bit more.

Now we’ve added a new member to the GroupInfo object that will show the total size of all files in each group by MB. Don’t forget to use -Passthru to force PowerShell to write the new object back to the pipeline so it can be saved in the grouped variable. Finally, the result:

fileage-04

And there you go. Because we’re working with objects, adding new information is really quite easy. Certainly much easier than trying to do something like this in VBScript! And even if you don’t need this specific solution, I hope that you picked up a technique or two.

Friday Fun – Get Number Object

You most likely know that I’m all about the object and the PowerShell pipeline. Everything in PowerShell is an object. Pipe something to Get-Member and you can discover all of the object’s properties and methods (ie its members). Some objects, like strings, have many methods but very few properties. Some objects, like numbers have very little of either. I mean, what can you really do with a number? Well, I can have a bit of fun with one and maybe teach a few PowerShell concepts along the way. Continue reading

All Hail Dir UseALot!

Some of you know my relationship with the a command prompt goes back a long, long way. Naturally I became very adept at using the DIR command, fully taking advantage of its switches to tease out hidden information or to quickly get just the information I wanted. When PowerShell first came out, I made the transition to the DIR alias without too much difficulty. Although I still found myself wanting to run a command like DIR /ad  (ie list only directories). Yes, you can achieve the same results with the PowerShell cmdlets, but that takes too much typing, especially for something I might want to use on a regular basis. I finally got around to writing a DIR function for PowerShell that better emulates my beloved DIR command from the CMD shell. Continue reading