Replace string in variable from data in a text file in Powershell

Question

I have a powershell script that returns lines whose info will be ingested by Splunk in order to monitor DHCP Free Addresses.

The output is already heavily "treated", it looks like this (the &&& is a Splunk event breaker):

Subnet=10.31.3.0
AddressesInUse=0
AddressesFree=249
&&&
Subnet=10.31.4.0
AddressesInUse=0
AddressesFree=249
&&&
Subnet=10.31.9.0
AddressesInUse=0
AddressesFree=249
&&&
Subnet=10.32.1.0
AddressesInUse=32
AddressesFree=177
&&&
Subnet=10.34.1.0
AddressesInUse=98
AddressesFree=111
&&&

Though, I have a exception list with subnets values that must be ignored. I'm planing to write them to a text file, Get-Content from it, and replace the Subnet values in the variable (from the command result) that are -eq to any of the text file lines, turning it to "" (and then I'm planing to ignore them in Splunk with "IfNull(SubnetValue) then ignore event").

The expected results should look like this:

File SubnetExceptions.txt content example:

10.32.1.0
10.34.1.0

Expected result:

Subnet=10.31.3.0
AddressesInUse=0
AddressesFree=249
&&&
Subnet=10.31.4.0
AddressesInUse=0
AddressesFree=249
&&&
Subnet=10.31.9.0
AddressesInUse=0
AddressesFree=249
&&&
Subnet=
AddressesInUse=32
AddressesFree=177
&&&
Subnet=
AddressesInUse=98
AddressesFree=111
&&&

So that the ones that I wanted to ignore would come off as "null" values to Splunk, solving my problem :)

I've done a bit of replacing in my life, but never from a text file. My tests failed miserably. Could anyone help me to do it?

Thanks!

David

Vincent K · Accepted Answer · 2017-12-14 13:12:57Z

1

This code will join your ip in regex format to replace the ip

"$((Get-Content 'C:\Vincent\Test\IP.txt') -join '$|')$"
10.32.1.0$|10.34.1.0$

or

"Subnet=$((Get-Content 'C:\Vincent\Test\IP.txt') -join '$|Subnet=')$",'Subnet='
Subnet=10.32.1.0$|Subnet=10.34.1.0$

Code to replace IP:

(Get-Content 'C:\Vincent\Test\Test.txt') -replace "$((Get-Content 'C:\Vincent\Test\IP.txt') -join '$|')$`"

or

(Get-Content 'C:\Vincent\Test\Test.txt') -replace "Subnet=$((Get-Content 'C:\Vincent\Test\IP.txt') -join '$|Subnet=')$",'Subnet='

edited Dec 14, 2017 at 13:12

answered Dec 14, 2017 at 12:40

Vincent K

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Comments

Esperento57 · Accepted Answer · 2017-12-16 09:39:09Z

1

Something like this?

$ExceltpionList=get-content C:\temp\SubnetExceptions.txt

Get-Content C:\temp\spunkfile.txt | %{

$CurrentRow=$_

$ExceltpionList | %{

    if ($CurrentRow -eq "Subnet=$_")
    {
        $CurrentRow=$CurrentRow -replace "Subnet=$_", "Subnet="

    }
}

$CurrentRow

}

answered Dec 16, 2017 at 9:39

Esperento57

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Comments

Palle Due · Accepted Answer · 2017-12-14 12:56:22Z

0

Provided your output is in a file result.txt you can do this:

$content = Get-Content "result.txt"
cat "subnetexceptions.txt" | %{ $content = $content -replace $_,"IGNORE"}

If you need to save to file just add

$content > newfile.txt

I tested it and it works.

edited Dec 14, 2017 at 12:56

answered Dec 14, 2017 at 12:03

Palle Due

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3 Comments

David Lago Over a year ago

Thanks for the answer. I don't think I got it haha. Let me show you how I am doing this: > Out-File -InputObject $Result -filepath "c:\Scripts\Result.txt" > Get-Content "c:\Scripts\Result.txt" | cat SubnetExceptions.txt | %{ $Subnet = $_; | {$_ -replace $Subnet,"IGNORE"} }

David Lago Over a year ago

Also tried with the variable itself, without outputting it into a "result" file.

Palle Due Over a year ago

I've edited my answer. The first one was a little hasty.

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