Replace First Occurrence of a String in a Multi-line String with PowerShell

Again a very simple post about a simple thing which I cannot find a satisfactory answer for on the Internet.

How do you replace the first instance of a string in a multiline string in PowerShell?

You have the following and you want to replace the first “<tr>”.

<table>

    <tbody>

        <tr>

               <td>2017-12-12 01:39:40</td>

               <td>User Provisioning Completed</td>

        </tr>

    </tbody>

</table>

Latest versions of PowerShell have 3 arguments for the "replace" method with the last one being exactly that – the number of occurrences from the beginning that will be replaced. But I write scripts that have to run in numerous environments and adding PowerShell update prerequisite just for that seems like overkill.

My exact scenario is that I want to add a value in the top of a table, so I’m replacing the first “<tr>” with the new value and keeping this existing “<tr>”.

Here is my solution:

####This is the string that we will replace in

$initialString = @"

<table>

    <tbody>

        <tr>

               <td>2017-12-12 01:39:40</td>

               <td>User Mail Created</td>

        </tr>

    </tbody>

</table>

"@

####This is the string that will be the replacement.

$ireplacementString = @"

<tr>

               <td>2017-12-12 01:50:17</td>

               <td>User Provisioning Completed</td>

        </tr>

        <tr>

"@

####Add Regex to Replacement String

$replacementConstruct=@'

$1{0}

'@ -f $ireplacementString

####Replace the first occurance of "<tr>" with the content of Replacement String.

$finalResult = $initialString -replace '^((?s).*?)<tr>', $replacementConstruct