Simple Example: Expressions are only allowed as the first element of a pipeline

Question

Can explain why philosophically this doesn't work? Just as a learning example, I wanted to see the properties of the get-service cmdlet, without the events or methods.

PS C:\Users\Neal> get-service | get-member |  {$_.name -eq "Property"}

Result:

At line:1 char:29
+ get-service | get-member |  {$_.name -eq "Property"}
+                             ~~~~~~~~~~~~~~~~~~~~~~~~
Expressions are only allowed as the first element of a pipeline.
    + CategoryInfo          : ParserError: (:) [], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : ExpressionsMustBeFirstInPipeline

score 5 · Accepted Answer · edited May 23 '17 at 11:48

5

{$_.name -eq "Property"} is just a scriptblock. If you want to use Where-Object to filter the results of get-member, you need to type Where-Object:

PS C:\Users\Neal> get-service | get-member | Where-Object {$_.name -eq "Property"}

or you can use where, which is an alias for Where-Object:

PS C:\Users\Neal> get-service | get-member | where {$_.name -eq "Property"}

There is even a special character ? which refers to Where-Object:

PS C:\Users\Neal> get-service | get-member | ? {$_.name -eq "Property"}

All three examples given above do the same thing. Choosing between them is simply a matter of style.

edited May 23 '17 at 11:48

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answered Oct 06 '14 at 20:01

Thanks, so sometimes, for example, on the first expression only, you can actually leave off the word "where" – NealWalters Oct 06 '14 at 20:03
or just `Get-Member -MemberType Properties` without piping to Where – TheMadTechnician Oct 06 '14 at 20:04
That's much better! (And in the example I posted, I meant to have $_.MemberType not $_.Name). – NealWalters Oct 06 '14 at 20:05

Simple Example: Expressions are only allowed as the first element of a pipeline

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