How to get the captured groups from Select-String?

Question

I\'m trying to extract text from a set of files on Windows using the Powershell (version 4):

PS > Select-String -AllMatches -Pattern 

        

Answer 1

This script will grab a regex's specified capture group from a file's content and output its matches to console.

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$file is the file you want to load
$cg is capture group you want to grab
$regex is the regular expression pattern

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Example file and its content to load:

C:\some\file.txt

This is the especially special text in the file.

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Example Use: .\get_regex_capture.ps1 -file "C:\some\file.txt" -cg 1 -regex '\b(special\W\w+)'

Output: special text

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get_regex_capture.ps1

Param(
    $file=$file,
    [int]$cg=[int]$cg,
    $regex=$regex
)
[int]$capture_group = $cg
$file_content = [string]::Join("`r`n", (Get-Content -Raw "$file"));
Select-String -InputObject $file_content -Pattern $regex -AllMatches | % { $_.Matches.Captures } | % { echo $_.Groups[$capture_group].Value }