Regular expression escaping in PowerShell

Question

I have a regular expression that works perfectly in Sublime text, or other text editors, and it does exactly what I need it to do.

Here is the regular expression

(?sm),"([\w\W]*?)Date completed:

The problem is, in PowerShell, it just doesn't do anything.

This is my little script

$text = Get-Content c:\Tools\export.csv
$text -replace '(?sm),"([\w\W]*?)Date completed: ','REPLACED' | Out-File output.csv

If I replace the regular expression by plain text, it works great. So what is it that it does not like in my regular expression?

Thanks!

if I replace the regular expression by something like 'Example' it will find Example and replace it with REPLACED. — JonYork
– JonYork, Commented Apr 8, 2016 at 18:12
That comma and open double quote in here '(?sm),"([\w\W]*?)Date completed: ' it is expecting a comma and double quote which I don't think exists in your source data that you are not including here. More impotantly you need to change you $text to be a single string if you expect to use the single and multi mode. $text = Get-Content c:\Tools\export.csv | out-string... im just doing to write and answer. — Matt
– Matt, Commented Apr 8, 2016 at 18:25
If a regex is not working we need source examples. Else it is impossible to know what is wrong. Show us how you made it work. — Matt
– Matt, Commented Apr 8, 2016 at 18:28

Matt · Accepted Answer · 2016-04-08 18:38:06Z

1

Regardless of what you are trying to match against when you use single and multimode those are supposed to work on multi-lined strings. Get-Content by default will return a string array. -replace functions as an array operator and will run that pattern against each line individually.

So for starters make $text one string.

$text = Get-Content c:\Tools\export.csv | Out-String

Or if you have at least PowerShell 3.0

$text = Get-Content c:\Tools\export.csv -Raw

answered Apr 8, 2016 at 18:38

Matt

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JonYork · Accepted Answer · 2016-04-11 14:53:48Z

0

Based on the info I got from the people who answered, here is how I was able to accomplish what I needed to do for the regular expression

$text = (Get-Content c:\Tools\export.csv) | out-string

$regex = "(?sm),""\s.*?Date completed: "
$replace = ',"'
$output = [regex]::replace($text,$regex,$replace)

$output | Out-file c:\Tools\output.csv -Encoding ascii

answered Apr 11, 2016 at 14:53

JonYork

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