Powershell replace lose line breaks

Question

I am a newbie in powershell. I have a simple powershell script that just replace text but I found that the regex replace turn my multiline data source into a single line text when the output is produced. I want the line breaks to be preserved. Here is the dumb down version of the script.

$source=(Get-Content textfile.txt)

$process1 = [regex]::Replace($source, "line", "line2")

$process1 | out-file -encoding ascii textfile2.txt

You can create a test file call textfile.txt with simple lines like this to test it

line 
line
Some line
More line here

Have I missed something obvious?

Thanks, Fadrian

score 21 · Accepted Answer · edited Apr 28 '10 at 07:41

21

Your problem here is that Get-Content returns a string[] (with one item for each line in the source file) while [regex]::Replace expects a string. That's why the array will first be converted to a string which simply means lumping together all items.

PowerShell provides a -replace operator which will handle this case more gracefully:

(Get-Content .\textfile.txt) -replace 'line', 'line2' | 
   out-file -encoding ascii textfile2.txt

The -replace operator operates on each item of an array individually i it's applied to an array.

And yes, it does regular expression matches and replaces. For example:

> (Get-Content .\textfile.txt) -replace '(i|o|u)', '$1$1'
liinee
liinee
Soomee liinee
Mooree liinee heeree

Read a bit more here and here.

edited Apr 28 '10 at 07:41

Joey

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answered Apr 28 '10 at 03:40

James Kolpack

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This works thanks. Still wonder why the regex behaves the way it is, different from actually running the regex in .NET environment. – Fadrian Sudaman Apr 28 '10 at 04:25
2

@Fadrian: I added a paragraph at the start of the answer explaining your original problem. Hope it helps. – Joey Apr 28 '10 at 07:42
Thanks Johannes +1 for reply and +1 for the post – Fadrian Sudaman Apr 28 '10 at 09:34

Powershell replace lose line breaks

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