Insert Content into Text File in Powershell

Question

I want to add content into the middle of a text file in Powershell. I'm searching for a specific pattern, then adding the content after it. Note this is in the middle of the file.

What I have currently is:

 (Get-Content ( $fileName )) |        Foreach-Object {             if($_ -match "pattern")            {                 #Add Lines after the selected pattern                 $_ += "`nText To Add"            }       }   } | Set-Content( $fileName ) 

However, this doesn't work. I'm assuming because $_ is immutable, or because the += operator doesn't modify it correctly?

What's the way to append text to $_ that will be reflected in the following Set-Content call?

Answer 1

Just output the extra text e.g.

(Get-Content $fileName) |      Foreach-Object {         $_ # send the current line to output         if ($_ -match "pattern")          {             #Add Lines after the selected pattern              "Text To Add"         }     } | Set-Content $fileName 

You may not need the extra ``n` since PowerShell will line terminate each string for you.

Answer 2

How about this:

(gc $fileName) -replace "pattern", "$&`nText To Add" | sc $fileName 

I think that is fairly straight-forward. The only non-obvious thing is the "$&", which refers to what was matched by "pattern". More info: http://www.regular-expressions.info/powershell.html