How can I make a useable table from vssadmin list writers in Powershell?

Question

I need a table from vssadmin list writers with PowerShell and I only need the writer ID from the list of all the writers.

I tried your solution as below for shadowstorage but I was not able to get it work. Is it possible to help me sorting this out?

$pattern = 'for volume: \((.*?)\)[\s\S]*?' +
           'used.*?space: (\d+.*?b)[\s\S]*?' +
           'allocated.*?space: (\d.*?b)'

& vssadmin list shadowstorage | Out-String |
  Select-String $pattern -AllMatches |
  Select-Object -Expand Matches |
  ForEach-Object {
    New-Object -Type PSObject -Property @{
      ComputerName   = $env:COMPUTERNAME
      Drive          = $_.Groups[1].Value
      UsedSpace      = $_.Groups[2].Value
      AllocatedSpace = $_.Groups[3].Value
    }
  }

Answer 1

You don't need the overhead of creating custom object if you just want a list of single values. Simply matching lines with the string "Writer Id:" should give you just the lines with the IDs:

& vssadmin list writers | Select-String -Pattern 'Writer Id:'

By using a positive lookbehind assertion (?<=...) in the pattern you could even extract just the ID from the matching lines:

& vssadmin list writers |
    Select-String -Pattern '(?<=Writer Id: ).*' |
    Select-Object -Expand Matches |
    Select-Object -Expand Value

Alternatively you could use a combination of the -match and -replace operators to the same end:

(& vssadmin list writers) -match 'Writer Id:' -replace '^.*: '

The above matches lines containing the string "Writer Id:" and then removes everything from the beginning of the line (^) up to and including the colon and space, leaving just the ID.