PowerShell Parameters
PowerShell parameters are used to pass arguments to functions, scripts, or cmdlets, allowing for flexible and reusable code. Here’s a comprehensive guide on PowerShell parameters, including how to define, use, and manage them.
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Defining Parameters
Parameters in PowerShell functions or scripts are defined using the param block or the [Parameter()] attribute within the function definition.
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Using the param Block
The param block is placed at the beginning of the script or function and is used to define the parameters.
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function Get-Sample {
param (
[string]$Name,
[int]$Age
)
Write-Output "Name: $Name, Age: $Age"
}
Get-Sample -Name "John" -Age 30
Using the [Parameter()] Attribute
The [Parameter()] attribute allows for more detailed parameter configurations, such as making a parameter mandatory or setting a default value.
function Get-Sample {
param (
[Parameter(Mandatory=$true)]
[string]$Name,
[Parameter(Mandatory=$false)]
[int]$Age = 25
)
Write-Output "Name: $Name, Age: $Age"
}
Get-Sample -Name "John"
Parameter Attributes
PowerShell provides several attributes to control the behavior of parameters.
-
Mandatory: Specifies that the parameter is required.
-
DefaultValue: Sets a default value for the parameter.
-
Position: Defines the position of the parameter when calling the function without named parameters.
-
ValueFromPipeline: Indicates that the parameter can accept values from the pipeline.
-
ValueFromPipelineByPropertyName: Accepts values from the pipeline based on the property name.
function Get-UserInfo {
param (
[Parameter(Mandatory=$true, Position=0)]
[string]$Username,
[Parameter(Position=1, ValueFromPipeline=$true)]
[string]$Email
)
process {
Write-Output "Username: $Username, Email: $Email"
}
}
"john@example.com" | Get-UserInfo -Username "John"
