Powershell regex only select digits - regex

Question

I have a script that I am working on to parse each line in the log. My issue is the regex I use matches from src= until space.
I only want the ip address not the src= part. But I do still need to match from src= up to space but in the result only store digits. Below is what I use but it sucks really badly. So any help would be helpful
#example text
$destination=“src=192.168.96.112 dst=192.168.5.22”
$destination -match 'src=[^\s]+'
$result = $matches.Values
#turn it into string since trim doesn’t work
$result=echo $result
$result=$result.trim(“src=”)

Answer 1

You can use a lookbehind here, and since -match only returns the first match, you will be able to access the matched value using $matches[0]:
$destination -match '(?<=src=)\S+' | Out-Null
$matches[0]
# => 192.168.96.112
See the .NET regex demo.
(?<=src=) - matches a location immediately preceded with src=
\S+ - one or more non-whitespace chars.
To extract all these values, use
Select-String '(?<=src=)\S+' -input $destination -AllMatches | Foreach {$_.Matches} | Foreach-Object {$_.Value}
or
Select-String '(?<=src=)\S+' -input $destination -AllMatches | % {$_.Matches} | % {$_.Value}

Answer 2

Another way could be using a capturing group:
src=(\S+)
Regex demo | Powershell demo
For example
$destination=“src=192.168.96.112 dst=192.168.5.22”
$pattern = 'src=(\S+)'
Select-String $pattern -input $destination -AllMatches | Foreach-Object {$_.Matches} | Foreach-Object {$_.Groups[1].Value}
Output
192.168.96.112
Or a bit more specific matching the dot and the digits (or see this page for an even more specific match for an ip number)
src=(\d{1,3}(?:\.\d{1,3}){3})