PowerShell script to monitor IIS logs for 500 errors every 10 minutes

I'm trying to set up a script to monitor IIS 7.5 logs fro 500 errors. Now I can get it to do that OK but I would like it to check every 30 minutes. Quite naturally I don't want it to warn me about the previous 500 errors it has already reported.

As you can see from the script below I have added a $time variable to take this into account, however I can't seem to find a way to use this variable. Any help would be appreciated.

#Set Time Variable -30
$time = (Get-Date -Format hh:mm:ss (Get-Date).addminutes(-30))
# Location of IIS LogFile
$File = "C:\Users\here\Documents\IIS-log\"+"u_ex"+(get-date).ToString("yyMMdd")+".log"
# Get-Content gets the file, pipe to Where-Object and skip the first 3 lines.
$Log = Get-Content $File | where {$_ -notLike "#[D,S-V]*" }
# Replace unwanted text in the line containing the columns.
$Columns = (($Log[0].TrimEnd()) -replace "#Fields: ", "" -replace "-","" -replace "\(","" -replace "\)","").Split(" ")
# Count available Columns, used later
$Count = $Columns.Length
# Strip out the other rows that contain the header (happens on iisreset)
$Rows = $Log | where {$_ -like "*500 0 0*"}
# Create an instance of a System.Data.DataTable
#Set-Variable -Name IISLog -Scope Global
$IISLog = New-Object System.Data.DataTable "IISLog"
# Loop through each Column, create a new column through Data.DataColumn and add it to the DataTable
foreach ($Column in $Columns) {
  $NewColumn = New-Object System.Data.DataColumn $Column, ([string])
  $IISLog.Columns.Add($NewColumn)
}
# Loop Through each Row and add the Rows.
foreach ($Row in $Rows) {
 $Row = $Row.Split(" ")
 $AddRow = $IISLog.newrow()
 for($i=0;$i -lt $Count; $i++) {
 $ColumnName = $Columns[$i]
 $AddRow.$ColumnName = $Row[$i]
}
 $IISLog.Rows.Add($AddRow)
 }
 $IISLog | select time,csuristem,scstatus

OK With KevinD's help and PowerGUI with a fair bit of trial and error, I got it working as I expected. Here's the finished product.

#Set Time Variable -30
$time = (Get-Date -Format "HH:mm:ss"(Get-Date).addminutes(-30))
# Location of IIS LogFile
$File = "C:\Users\here\Documents\IIS-log\"+"u_ex"+(get-date).ToString("yyMMdd")+".log"
# Get-Content gets the file, pipe to Where-Object and skip the first 3 lines.
$Log = Get-Content $File | where {$_ -notLike "#[D,S-V]*" }
# Replace unwanted text in the line containing the columns.
$Columns = (($Log[0].TrimEnd()) -replace "#Fields: ", "" -replace "-","" -replace "\(","" -replace "\)","").Split(" ")
# Count available Columns, used later
$Count = $Columns.Length
# Strip out the other rows that contain the header (happens on iisreset)
$Rows = $Log | where {$_ -like "*500 0 0*"}
# Create an instance of a System.Data.DataTable
#Set-Variable -Name IISLog -Scope Global
$IISLog = New-Object System.Data.DataTable "IISLog"
# Loop through each Column, create a new column through Data.DataColumn and add it to the DataTable
foreach ($Column in $Columns) {
  $NewColumn = New-Object System.Data.DataColumn $Column, ([string])
  $IISLog.Columns.Add($NewColumn)
}
# Loop Through each Row and add the Rows.
foreach ($Row in $Rows) {
  $Row = $Row.Split(" ")
  $AddRow = $IISLog.newrow()
  for($i=0;$i -lt $Count; $i++) {
    $ColumnName = $Columns[$i]
    $AddRow.$ColumnName = $Row[$i]
  }
  $IISLog.Rows.Add($AddRow)
  }
  $IISLog | select @{n="Time"; e={Get-Date -Format "HH:mm:ss"("$($_.time)")}},csuristem,scstatus | ? { $_.time -ge $time }

Thanks again Kev you're a good man. Hope this code helps someone else out there.

Here's

Solution

Try changing your last line to:

$IISLog | select @{n="DateTime"; e={Get-Date ("$($_.date) $($_.time)")}},csuristem,scstatus | ? { $_.DateTime -ge $time }

In the select, we're concatenating the date and time fields, and converting them to a date object, then selecting rows where this field is greater than your $time variable.

You'll also need to change your $time variable:

$time = (Get-Date).AddMinutes(-30)

You want a DateTime object here, not a string.