Powershell Nested Replace - powershell

Question

I am looping through multiple remote machines looking for a certain string to appear in a log file (other things are being collected from each device but for simplicity I've left that out). When I find them I want to return them and write to a central log, this is all working perfectly, except I want to tidy up the central log, by removing information from each string.
So I start with
**28-Jan-2021 01:31:49,TCPServer.run(),3,JMX TCP Server running on 8085
But want to save to Central Log
28-Jan-2021 01:31:349,JMX TCP 8085
And I can achieve this using the below, but surely there is a more succinct way to do this? (have played about with -Replace but no joy)
$JMXString8085 = $JMXString8085.Replace("TCPServer.run(),3,","")
$JMXString8085 = $JMXString8085.Replace("}","")
$JMXString8085 = $JMXString8085.Replace(" Server running on","")

Answer 1

[...] surely there is a more succinct way to do this? (have played about with -Replace but no joy)
There is, and -replace can indeed help us here. -replace is a regex operator, it performs text replacement using regular expressions - patterns we can use to describe strings that we might not be quite sure the exact contents of.
For a string like:
$string = '**28-Jan-2021 01:31:49,TCPServer.run(),3,JMX TCP Server running on 8085'
... we could describe the fields in between the commas, and use that to tell PowerShell to only preserve some of them for example:
PS ~> $string -replace '^\*\*([^,]+),[^,]+,[^,]+,([^,]+) Server running on (\d+)', '$1,$2 $3'
28-Jan-2021 01:31:49,JMX TCP 8085
The pattern I used in this example (^\*\*([^,]+),[^,]+,[^,]+,([^,]+) Server running on (\d+)) might seem a bit alien at first, so let's try and break it down:
^ # carret means "start of string"
\*\* # Then we look for two literal asterisks
( # This open parens means "start of a capture group"
[^,]+ # This means "1 or more characters that are NOT a comma", captures the timestamp
) # And this matching closing parens means "end of capture group"
, # Match a literal comma
[^,]+ # Same as above, this one will match "TCPServer.run()"
, # Same as above
[^,]+ # You probably get the point by now
, # ...
( # This open parens means "start ANOTHER capture group"
[^,]+? # The `?` at the end means "capture as few as possible", captures "JMX TCP"
) # And this matching closing parens still means "end of capture group"
Server... # Just match the literal string " Server running on "
( # Finally a THIRD capture group
\d+ # capturing "1 or more digits", in your case "8085"
) # and end of group
Since our pattern "captures" a number of substrings, we can now refer to these individual substrings in out substition pattern $1,$2 $3, and PowerShell will replace the $N references with the capture group value.

Answer 2

here is yet another way to do the job. [grin]
what it does ...
assigns the string to a $Var
chains .Replace() to get rid of the asterisks and the "Server" phrase
splits on the , chars
takes the 1st & 4th items from that split
joins them into one string with , [comma then space] for a delimiter
assigns that to a new $Var
displays the results
the code ...
$InString = '**28-Jan-2021 01:31:49,TCPServer.run(),3,JMX TCP Server running on 8085'
$OutString = ($InString.Replace('**', '').Replace('Server running on ', '').Split(',')[0, 3]) -join ', '
$OutString
output ...
28-Jan-2021 01:31:49, JMX TCP 8085