PowerShell excels at manipulating objects, the heart of most data it works with. This blog post dives into the essential object manipulation cmdlets, empowering you to filter, sort, format, group, and analyze data effectively in your scripts.
1. Select-Object: Picking the Perfect Properties
This cmdlet allows you to choose specific properties you want to display from an object. Here’s how it works:
PowerShell
Get-Process | Select-Object Name, CPU -ExpandProperty Name # Select Name and CPU properties, then expand Name into a list
This command retrieves process information, selects only the “Name” and “CPU” properties, and then expands the “Name” property into a list of process names.
2. Sort-Object: Arranging Objects in Order
This cmdlet lets you sort objects based on specific properties. Sort order can be ascending or descending.
PowerShell
Get-Service | Sort-Object Status # Sort services by their Status property
Get-Process | Sort-Object CPU -Descending # Sort processes by CPU usage (descending order)
The first command sorts services by their “Status” property. The second command sorts processes based on their CPU usage, with the most resource-intensive processes listed first.
3. Measure-Object: Analyzing Object Statistics
This cmdlet calculates statistical information about objects, such as count, average, minimum, and maximum values for specific properties.
PowerShell
Get-Process | Measure-Object -Property CPU -Average # Calculate average CPU usage for all processes
Get-Service | Measure-Object -Property @{Name="RunningServices"; Expression{$_.Status -eq "Running"}} # Count running services
The first command calculates the average CPU usage across all processes. The second command uses a calculated property to count only running services.
4. Group-Object: Categorizing Objects by Shared Values
This cmdlet groups objects based on a specific property, allowing you to analyze data by category.
PowerShell
Get-Process | Group-Object Status # Group processes by their Status property
Get-Service | Group-Object Name -NoElement # Group services by Name but hide individual service details
The first command groups processes based on their “Status” (Running, Stopped, etc.). The second command groups services by “Name” but hides the details of each service within the group.
5. Where-Object: Filtering Objects Based on Conditions
This cmdlet allows you to filter objects based on specific criteria. You can use comparison operators and wildcards for flexible filtering.
PowerShell
Get-Process | Where-Object {$_.Name -like "*notepad*"} # Filter processes with "notepad" in their name
Get-Service | Where-Object {$_.Status -eq "Stopped" -and $_.Name -notlike "*sql*"} # Filter for stopped services except those with "sql" in their name
The first command filters for processes containing “notepad” in their name. The second command filters for stopped services, excluding those with names containing “sql.”
6. ForEach-Object: Processing Objects Individually
This cmdlet allows you to iterate through each object in a collection and perform an action on each one.
PowerShell
Get-Process | ForEach-Object { Write-Host "Process Name: ${\_.Name}, CPU: ${\_.CPU}%"} # Display details for each process
Get-Service | ForEach-Object { Stop-Service $_.Name -Force # Stop all running services (use with caution)
The first command iterates through each process and displays its name and CPU usage. The second command (use with caution) iterates through each service and stops it forcefully.
7. New-Object: Constructing Custom Objects
This cmdlet allows you to create new objects with specific properties and values. This can be useful for storing data or building complex data structures.
PowerShell
$computerInfo = New-Object PSObject -Property @{
"ComputerName" = "Server1"
"OSVersion" = "Windows 10"
"Memory" = (Get-WmiObject Win32_OperatingSystem).TotalVisibleMemorySize / 1MB
}
Write-Host $computerInfo # Display the newly created object with its properties
This code creates a new object named $computerInfo with three properties: “ComputerName,” “OSVersion,” and “Memory.” The “Memory” property retrieves the total visible memory size from the system and converts it to megabytes.