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regexpowershell
justSteve
justSteve

Reputation: 5524

Powershell RegEx not being invoked on piped output

Developed this statement on my primary workstation where it (correctly) outputs a delimited textfile:

type output.tmp | -match /r /v "^-[-|]*-.$"  >  output.csv

Now, working on my laptop (same win8.1) where supposedly all the same PS modules and snapins are loaded, it tosses an error: 

-match : The term '-match' is not recognized as the name of a cmdlet,

Yet: 

"Software" –match "soft"

works.

1) Why?

2) Is there a PS commandlet I should invoke to be able to get a more verbose/helpful error output?

thx

Upvotes: 0

Views: 307

Answers (3)

Richard
Richard

Reputation: 109130

-match is an operator on two arguments (one placed before one after the -match).

But at the beginning of each pipeline segment you need a command (including cmdlets)1.

There are two approaches:

  1. Wrap the -match into a cmdlet like foreach-object (or its % alias):

    ... | %{ $_ -match $regex } | ...

    remembering that -match returns a boolean, not the matched text.

  2. Use Select-String which is a cmdlet explicitly included for searching text. This does return the matched text (along with some other information), and can read a file itself:

    Select-String -Path $inputFile $regex

1 Strictly speaking: except the first, which can be any expression.

Upvotes: 2

Eris
Eris

Reputation: 7638

  1. To get obnoxious amounts of debug output, get-Help Set-PSDebug

  2. You simply need to add the following:

    type output.tmp | ? { $_ -match /r /v "^-[-|]*-.$" } > output.csv

Or the more powershell-y way:

Get-Content -Path:"Output.Tmp" | Where { $_ -match "^-[-|]*-.$" } | Out-File -FilePath:"output.csv"

Upvotes: 0

Alex Filipovici
Alex Filipovici

Reputation: 32571

The reason for the error is that match is a comparison operator, not a cmdlet:

Comparison operators let you specify conditions for comparing values and finding values that match specified patterns. To use a comparison operator, specify the values that you want to compare together with an operator that separates these values.

Also:

The match operators (-Match and -NotMatch) find elements that match or do not match a specified pattern using regular expressions.

The syntax is:

<string[]> -Match <regular-expression>
<string[]> -NotMatch <regular-expression>

The following examples show some uses of the -Match operator:

PS C:\> "Windows", "PowerShell" -Match ".shell"
PowerShell

PS C:\> (Get-Command Get-Member -Syntax) -Match "-view"
True

PS C:\> (Get-Command Get-Member -Syntax) -NotMatch "-path"
True

PS C:\> (Get-Content Servers.txt) -Match "^Server\d\d"
Server01
Server02

The match operators search only in strings. They cannot search in arrays of integers or other objects.

So, the correct syntax is:

@(type output.tmp) -match "^-[-|]*-.$" > output.csv

Note: Just as @mjolinor suggested, the @ prefix forces the (type output.tmp) into an array, just in case that the input file contains only one line.

Upvotes: 1

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