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about_Simplified_Syntax

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Short description

Describes easier, more natural-language ways of scripting filters for collections of objects.

Long description

Simplified syntax, introduced in Windows PowerShell 3.0, lets you build some filter commands without using script blocks. The simplified syntax more closely resembles natural language, and is primarily useful with collections of objects that get piped into commands Where-Object and ForEach-Object and their corresponding aliases where and foreach.

You can use a method on the members of a collection (most commonly, an array) without referring to the automatic variable $_ inside a script block.

Consider the following two invocations:

Standard Syntax

dir Cert:\LocalMachine\Root | where { $_.FriendlyName -eq 'Verisign' }
dir Cert:\ -Recurse | foreach { $_.GetKeyAlgorithm() }

Simplified syntax

Under the simplified syntax, comparison operators that work on members of objects in a collection are treated as parameters. You can invoke a method on objects in a collection without referring to the automatic variable $_ inside a script block. Compare the following two invocations to those of the previous example:

dir Cert:\LocalMachine\Root | where FriendlyName -eq 'Verisign'
dir Cert:\ -Recurse | foreach GetKeyAlgorithm

While both syntaxes work, the simplified syntax returns results without referring to the automatic variable $_ inside a script block. The method name GetKeyAlgorithm is treated as a parameter of ForEach-Object. The second command returns the same results, but without errors, because the simplified syntax does not attempt to return results for items for which the specified argument did not apply.

In this example, the Process property Description is passed as the member name parameter to the ForEach-Object command. The results are descriptions of active processes.

Get-Process | foreach Description

In this example, the DirectoryInfo method GetFiles is passed as the member name parameter of the ForEach-Object command. The method is called with the search pattern parameter .*. The results are FileInfo records for all Unix-style hidden files in user home directories.

Get-ChildItem /home -Directory | foreach GetFiles .*

See also