Powershell - Monitoring live log file Q2 - powershell

Question

I had made an initial question here Which was answered but as i move along in my task I'm running into another problem.
Summary: I have a log file that's being written to via a serial device. I'm wanting to monitor this log file for particular strings (events) and when they happen i want to write those strings to a separate file.
Executing this one off does what I'm looking for:
$p = #("AC/BATT_PWR","COMM-FAULT")
$fileName = "SRAS_$(Get-Date -format yyyy-MM-dd).log"
$fullPath = "C:\temp\SRAS\$fileName"
Get-Content $fullpath -tail 1 -Wait | Select-String -Pattern $p -SimpleMatch | Out-File -Filepath C:\temp\SRAS\sras_pages.log -Append
The problem is the logfile gets a datestamp, putty saves it as SRAS_yyyy-mm-dd.log. So when the clock passes midnight this will no longer be looking at the correct file.
I found this post on SO which is exactly what I want to do, the OP claims it works for him. I modified it slightly for my purposes but it doesn't write events matching the desired strings to sras_pages.log
This is the 'modified' code:
while($true)
{
$now = Get-Date
$fileName = "SRAS_$(Get-Date -format yyyy-MM-dd).log"
$fullPath = "C:\temp\SRAS\$fileName"
$p = #("AC/BATT_PWR","COMM-FAULT")
Write-Host "[$(Get-Date)] Starting job for file $fullPath"
$latest = Start-Job -Arg $fullPath -ScriptBlock {
param($file)
# wait until the file exists, just in case
while(-not (Test-Path $fullpath)){ sleep -sec 10 }
Get-Content $file -Tail 1 -wait | Select-String -Pattern $p |
foreach { Out-File -Filepath "C:\temp\SRAS\sras_pages.log" -Append }
}
# wait until day changes, or whatever would cause new log file to be created
while($now.Date -eq (Get-Date).Date){ sleep -Sec 10 }
# kill the job and start over
Write-Host "[$(Get-Date)] Stopping job for file $fullPath"
$latest | Stop-Job
}
If I execute just the Get-Content segment of that code it does exactly what I'm looking for. I can't figure out what the issue is.
TIA for advice.

Answer 1

Here is a few suggested changes that should make it work:
$p does not exist within the job, add it as a parameter ($pattern in my example)
You are referring to $fullpath within your job (row 13), it should be $file.
Add parameter -SimpleMatch to select-string to search for literal strings instead of regular expressions. (This is not needed but will come in handy if you change search pattern)
Referring to $pattern instead of $p (see 1)
Skip the foreach on row 16.
Like this:
while($true)
{
$now = Get-Date
$fileName = "SRAS_$(Get-Date -format yyyy-MM-dd).log"
$fullPath = "C:\temp\SRAS\$fileName"
$p = #("AC/BATT_PWR","COMM-FAULT")
Write-Host "[$(Get-Date)] Starting job for file $fullPath"
$latest = Start-Job -Arg $fullPath, $p -ScriptBlock {
param($file,$pattern)
# wait until the file exists, just in case
while(-not (Test-Path $file)){ sleep -sec 10 }
Get-Content $file -Tail 1 -wait | Select-String -Pattern $pattern -SimpleMatch |
Out-File -Filepath "C:\temp\SRAS\sras_pages.log" -Append
}
# wait until day changes, or whatever would cause new log file to be created
while($now.Date -eq (Get-Date).Date){ sleep -Sec 10 }
# kill the job and start over
Write-Host "[$(Get-Date)] Stopping job for file $fullPath"
$latest | Stop-Job
}