PowerShell: Manipulate existing variable field values

Question

I feel like I'm missing something obvious but my mind's gone blank.....

I have the following output

PS C:\Users\User1> $TargetComputers

ComputerName   UninstallString                                                                               
------------   ---------------                                                                               
Server1        MsiExec.exe /I{A7E794A1-D6E9-43CC-9B69-DEB6B5A91EF9}                                          
Server2        MsiExec.exe /I{36648B37-EA03-4349-8C49-C26032D06C61}                                          
Server3        MsiExec.exe /I{36648B37-EA03-4349-8C49-C26032D06C61}                                          
Server4        C:\Program Files\7-Zip\Uninstall.exe                                                          
Server5        MsiExec.exe /I{A7E794A1-D6E9-43CC-9B69-DEB6B5A91EF9}                                          
Server6        MsiExec.exe /I{A7E794A1-D6E9-43CC-9B69-DEB6B5A91EF9}                                          
Server7        {"D:\Program Files\7-Zip\Uninstall.exe", MsiExec.exe /I{36648B37-EA03-4349-8C49-C26032D06C61}}
Server8        MsiExec.exe /I{A7E794A1-D6E9-43CC-9B69-DEB6B5A91EF9}                                          
Server9        MsiExec.exe /I{36648B37-EA03-4349-8C49-C26032D06C61}

How do I manipulate the UninstallString column to leave me just {GUID}, including literal path where specified, when I call $TargetComputers?

for most of those line, split on the {, take the 2nd part, split on the } and take the 1st part. for the lines that don't start with 'MsiExec.exe`, you will need to adjust what part you take after the splits. — Lee_Dailey
– Lee_Dailey, Commented Jan 28, 2021 at 19:10

zett42 · Accepted Answer · 2021-01-28 21:22:22Z

2

# Sample data
$TargetComputers = @(
    @{ ComputerName='server1'; UninstallString='MsiExec.exe /I{A7E794A1-D6E9-43CC-9B69-DEB6B5A91EF9}' }
    @{ ComputerName='server1'; UninstallString='{"D:\Program Files\7-Zip\Uninstall.exe", MsiExec.exe /I{36648B37-EA03-4349-8C49-C26032D06C61}}' }
    @{ ComputerName='server1'; UninstallString='C:\Program Files\7-Zip\Uninstall.exe' }
) | % { [PSCustomObject] $_ }

$TargetComputers | ForEach-Object { 
    $_.UninstallString = $_.UninstallString -replace '.*/I{(.+?)}.*', '$1' 
}

$TargetComputers

Output:

ComputerName UninstallString
------------ ---------------
server1      A7E794A1-D6E9-43CC-9B69-DEB6B5A91EF9
server1      36648B37-EA03-4349-8C49-C26032D06C61
server1      C:\Program Files\7-Zip\Uninstall.exe

Explanation:

By using the -replace operator, we are using regular expression (RegEx) pattern matching. The 1st string after -replace is the search string, the 2nd string is the substitute. If the RegEx doesn't match, the original string will be returned.
RegEx search string breakdown:
- .* - any character, zero or more times
- /I{ - literal sub string
- ( - starts a capture group
  - .+? - any character, one or more times, as little as possible
- ) - ends the capture group
- } - literal sub string
- .* - any character, zero or more times
RegEx substitute:
- $1 - replaces the string with the content of the 1st capture group (the GUID value)

edited Jan 28, 2021 at 21:22

answered Jan 28, 2021 at 21:08

zett42

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1 Comment

jshizzle Over a year ago

Thanks for this and the detailed explanation.

Stefano Paviot · Accepted Answer · 2021-01-28 20:24:32Z

0

Try with:

$TargetComputers = $TargetComputers | ForEach-Object {
  $matches = [Regex]::Matches($_.UninstallString, ({.*}),"IgnoreCase")
  if ( $null -ne $matches.Groups ) {
    $_.UninstallString = $matches.Groups[1].Value
  }

  return $_
}

edited Jan 28, 2021 at 20:24

answered Jan 28, 2021 at 19:32

Stefano Paviot

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