How to process out put of diskpart command using PowerShell - powershell

Question

I'm trying to capture volume number from diskpart command output. At present I'm doing it like this:
Using batch script:
#echo off
set VOLNO=''
set DRIVE=C
for /f "tokens=2,3" %%a in ('echo list volume ^| diskpart') do (
if %%b==%DRIVE% set VOLNO=%%a
)
echo Volume No. for C Drive is: %VOLNO%
Output:
Volume No. for C Drive is: 2
Using PowerShell:
$dp = "list volume" | diskpart | ? { $_ -match "^ [^-]" }>
$dp
Output:
Volume ### Ltr Label Fs Type Size Status Info
Volume 0 E DVD-ROM 0 B No Media
Volume 1 System Rese NTFS Partition 350 MB Healthy System
Volume 2 C NTFS Partition 59 GB Healthy Boot
Volume 3 D New Volume NTFS Partition 49 GB Healthy
I want to capture the Volume-Number e.g. it's 2 for C:\ to a variable using PowerShell.

Answer 1

Adjust your regular expression so that you can extract the desired information via capturing groups. I generally recommend building custom objects from the extracted information, to facilitate further processing.
Something like this should do what you want:
$drive = 'c'
'list volume' | diskpart | Where-Object {
$_ -match 'Volume (\d+)\s+([a-z])\s+'
} | ForEach-Object {
New-Object -Type PSObject -Property #{
'DriveLetter' = $matches[2]
'VolumeNumber' = [int]$matches[1]
}
} | Where-Object {
$_.DriveLetter -eq $drive
} | Select-Object -Expand VolumeNumber

Answer 2

A concise solution that uses -match to find the line of interest and the unary form of -split to split it into whitespace-separated tokens that can be accessed by index:
$drive = 'C'
$volNo = (-split (('list volume' | diskpart) -match " $drive "))[1]
"Volume No. for $drive Drive is: $volNo"
Note that diskpart must be run from an elevated session.