CODEWITHSUNDEEP
regexpowershellreplace
user1027442
user1027442

Reputation: 75

PowerShell - Replace contents of every tag using REGEX

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

Upvotes: 1

Views: 2986

Answers (2)

Miika L.
Miika L.

Reputation: 3353

I think the reason that you are left with just a single pair of start and end tags is because your query pattern finds three matches in the search string.

  1. The first pair of start and end.

  2. The second pair of start and end.

  3. The start from the first one, and the end tag from the second one (and if this match is found last, it will in fact replace all thats between the first and last with the new value).

So in your "(.*)" you might have to exclude any other start and end tags?

Upvotes: 0

Erik A. Brandstadmoen
Erik A. Brandstadmoen

Reputation: 10588

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;

Upvotes: 6

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