Question

I am trying to write a PowerShell script to replace the contents of tags i have put into an XML file. The tags appear multiple times within the XML, this is resulting in everything between the first and last tag being replaced as it is not stopping the first time the end tag is found.

I am using this:

$NewFile = (Get-Content .\myXML_file.xml) -join "" | foreach{$_ -replace "<!--MyCustom-StartTag-->(.*)<!--MyCustom-EndTag-->","<!--MyCustom-StartTag-->New Contents of Tag<!--MyCustom-EndTag-->"};
Set-Content .\newXMLfile.xml $newfile;

The file has contents like:

<!--MyCustom-StartTag-->
Lots of content
<!--MyCustom-EndTag-->
More stuff here
<!--MyCustom-StartTag-->
Lots of content    
<!--MyCustom-EndTag-->

And i am ending up with:

<!--MyCustom-StartTag-->
New Content Here    
<!--MyCustom-EndTag-->

Instead of:

<!--MyCustom-StartTag-->
New content
<!--MyCustom-EndTag-->
More stuff here
<!--MyCustom-StartTag-->
New content    
<!--MyCustom-EndTag-->

I have tried using: (?!MyCustom-StartTag) but that does work either.

Any ideas of what i should do to get this to work.

Thanks,
Richard

Answer 1

You should use the non-greedy version of *, namely *?. For more info, see: http://www.dijksterhuis.org/csharp-regular-expression-operator-cheat-sheet/ (Powershell uses same regex engine as C#).

$NewFile = (Get-Content .\myXML_file.xml) -join "" | foreach{$_ -replace "<!--MyCustom-StartTag-->(.*?)<!--MyCustom-EndTag-->","<!--MyCustom-StartTag-->New Contents of Tag<!--MyCustom-EndTag-->"};
Set-Content .\newXMLfile.xml $newfile;