Is there a shorter way to pull groups out of a Powershell regex?

Question

In PowerShell I find myself doing this kind of thing over and over again for matches:

some-command | select-string '^(//[^#]*)' |
     %{some-other-command $_.matches[0].groups[1].value}

So basically - run a command that generates lines of text, and for each line I want to run a command on a regex capture inside the line (if it matches). Seems really simple. The above works, but is there a shorter way to pull out those regex capture groups? Perl had $1 and so on, if I remember right. Posh has to have something similar, right? I've seen "$matches" references on SO but can't figure out what makes that get set.

I'm very new to PowerShell btw, just started learning.

score 15 · Accepted Answer · edited Jun 19 '09 at 13:13

15

You can use the -match operator to reformulate your command as:

some-command | Foreach-Object { if($_ -match '^(//[^#]*)') { some-other-command $($matches[1])}}

edited Jun 19 '09 at 13:13

Steven Murawski

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answered Jun 18 '09 at 06:58

Bas Bossink

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Eh? He's matching a line that starts with double-slash (//) and greedily matching up until (but excluding) the first hash (#). There is no end-of-line marker, so he's not specifically matching the entire line. – Peter Boughton Jun 18 '09 at 07:22
Yeah, that's the kind of thing I was looking for. Thanks for the edit, Bas. – scobi Jun 18 '09 at 15:35

score 8 · Answer 2 · answered Mar 07 '12 at 19:22

8

Named Replacement

'foo bar' -replace '(?<First>foo).+', '${First}'

Returns: foo

Unnamed Replacement

 'foo bar' -replace '(foo).+(ar)', '$2 z$2 $1'

Returns: ar zar foo

answered Mar 07 '12 at 19:22

Joe

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score 4 · Answer 3 · edited Jun 19 '09 at 13:11

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You could try this:

Get-Content foo.txt | foreach { some-othercommand [regex]::match($_,'^(//[^#]*)').value }

edited Jun 19 '09 at 13:11

Steven Murawski

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answered Jun 18 '09 at 08:18

Shay Levy

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For me this outputs a blank line if the input doesn't match. [Bas Bossink](http://stackoverflow.com/a/1011163/111424)'s answer works like this one but outputs only the matches. – Iain Samuel McLean Elder May 26 '14 at 20:18

Is there a shorter way to pull groups out of a Powershell regex?

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