Taking inventory of your servers can give you basic information about what’s taking up storage space. But fancy file attributes — such as its size, who created it, and how old it is — can be little harder to collect. Luckily, you can find all this and more using the Get-ChildItem cmdlet.
Get-ChildItem lets us list the items of one or more locations. In other words, it helps you get the child item (and other items, for that matter). This functionality is very similar to dir on Windows and ls on UNIX-like systems. In fact, dir and ls are aliases that you can use indirectly in PowerShell in place of Get-ChildItem.
As sysadmins, taking inventory of the workstations and servers that we manage is a necessary — but taxing — part of the job. We have probably all stressed ourselves out over similar questions at some point in our jobs:
Which workstations and servers are getting full on space?
Which users are hogging disk space?
Where are all my .mp3 files?
How many marshmallows can I fit into my mouth at once?
These are all important questions, and most can be answered using the Get-ChildItem command.
Get-ChildItem parameters
Get-ChildItem has many parameters to help us find our desired results.
Note that this list is not a complete list. It only shows the parameters we’ll be using today. Other popular parameters include the Name parameter, the Attributes parameter, the Depth parameter, the Include parameter, and the Exclude parameter. Microsoft offers a detailed overview of these parameters and whether they accept a wildcard character.
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Finding files in multiple locations
Deleting files that exist in multiple locations can free up precious space on your servers — if you can find them. Using Get-ChildItem, you can find and delete superfluous files instantly.
You can provide multiple paths as a string array or as several paths separated by commas, like the following example.
Get-ChildItem -Path Path1, Path2
Finding specific file types
We can use wildcards to specify file types. If we wanted to find all .txt files, we could use this:
Get-ChildItem *.txt
Finding large files
Sure, disk space is cheaper than ever, but that doesn’t mean we shouldn’t be proactive in utilizing our disk space efficiently.
PDQ Inventory does a great job at compiling reports and creating collections based on disk space. These reports make it easy to identify who has less than 25% disk space, for example. At a glance, I can tell that my workstation has 77% disk space free.
There is a lot of great information here, but what if you want to know which files are the suspected large files taking up your valuable disk space?
In this case, we’re going to look at the length (or size) of the files. For this example, I’ll specify that I want to see all files larger than 50 KB.
Get-ChildItem | Where-Object {$_.Length -gt 50KB}
The length is in bytes, so we can use a little trick to get the results back in megabytes (MB), which is far easier to read. In order to do this, we’ll need to specify the columns by name. Then, we’ll perform a calculation on the Length column.
Get-ChildItem | Where-Object {$_.Length -gt 50KB} | `
Select @{Name="Length";Expression={$_.Length/1MB}}, Name
Finding old files
This command can be used in a number of ways to locate files that are no longer needed in your system. You can include files that were created before a certain date (or within a specific time range), the date the file was last modified, and more.
In this case, we’re going to look at the LastWriteTime for each file. For the following example, I want to show all files older than 30 days. In order to do that, we have to get the current date with Get-Date, subtract 30 days, and then grab everything less than (older than) the resulting date.
Get-ChildItem | Where-Object {$_.LastWriteTime -lt (Get-Date).AddDays(-30)}
Combining techniques
The great thing about Get-ChildItem is that it allows you to kill several birds (or several hours of inventory) with one stone. You can combine these techniques, as well as others, to make a PowerShell script that works for you.
For instance, say you want to find all files in two paths (plus their respective subdirectories) that are older than 60 days and larger than 1 MB.
Easy peasy:
$time = (Get-Date).AddDays(-60)
$size = 1MB
Get-ChildItem Path1, Path2 -Recurse | `
Where-Object {$_.LastWriteTime -lt $time -and $_.Length -gt $size}Be certain to supply your own paths, of course.
Deleting found files
You can even take this a step further to delete the found files by piping them into Remove-Item. Just remember that by using the Force parameter, you'll have no warning when your files are deleted. Make certain that you know which files you're deleting.
<Insert your awesome script> | Remove-Item -Force -Recurse -ErrorAction SilentlyContinueNow you should be able to use Get-ChildItem to find a variety of file details in a variety of ways. You can use it to view the file system, the registry, or any provider.
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