Replace a line of text in a file using powershell 3

Question

I am trying to replace some text in a file. Currently I am replacing IP addresses with:

(Get-Content $editfile) | ForEach-Object { $_ -replace "10.10.37.*<", "10.10.37.$BusNet<" } | Set-Content $editfile

This code works well here. However I can't get the code to work with another line:

  <dbserver>SVRNAME</dbserver>

Here is the code I have written for this line:

(Get-Content $editfile) | ForEach-Object { $_ -replace "<dbserver>*</dbserver>", "$DbSVRName" } | Set-Content $editfile

The code above should replace SVRNAME with the DbSVRName. Yet it does not. I know it's simple, and I know I am going to feel dumb afterwards. What am I missing?

While debugging trying to find a solution I found that for some reason it can't see the *

(Get-Content $editfile) | ForEach-Object { $_ -match "<dbserver>*</dbserver>" }

This code reveals all falses results.

Does it work if you escape your slash? '<dbserver>*<//dbserver>' — Chris Anderson
– Chris Anderson, Commented Jul 23, 2015 at 1:26
Er wait, You want it to replace SVRNAME? Use -replace 'SVRNAME'. — Chris Anderson
– Chris Anderson, Commented Jul 23, 2015 at 1:27
Chris It does not escape with a //. the SVRNAME can be anything. — David
– David, Commented Jul 23, 2015 at 1:34

Chris Anderson · Accepted Answer · 2015-07-23 01:44:00Z

1

* doesn't capture stuff in regex, you need .* and specifically (.*?)

$str = 'text  <dbserver>SVRNAME</dbserver> text'
$replace = 'foo'

$str -replace '(<dbserver>)(.*?)(</dbserver>)', ('$1'+$replace+'$3')

Output

text  <dbserver>foo</dbserver> text

answered Jul 23, 2015 at 1:44

Chris Anderson

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2 Comments

David Over a year ago

That makes a lot of sense. Making each item a variable to search. I did not know this one. Thank you. Do you have a resource on this idea/topic? I would love to learn more about the technique you just showed me.

Chris Anderson Over a year ago

[1] for playing with regex expressions. Here's a decent post on -replace regex [2], but the magic is mostly a regex thing, not PowerShell in this case. There are lots of regex resources, just do some searches. [1]: regexpal.com [2]: powershell.org/wp/2013/08/29/…

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