Richard Siddaway's Blog

I will be presenting the above webcast next week.

Date: Wednesday, September 7, 2011

Time: 12:00 PM - 1:00 PM CST

Thats 6pm UK time

Register for the web cast at

http://powershell.com/cs/media/p/11256.aspx

A forum question about testing services and if they weren’t running got me thinking. I created an function to solve the question

function test-service{             
[CmdletBinding(SupportsShouldProcess=$true)]             
param (             
[parameter(Position=0,            
   ValueFromPipeline=$true,             
   ValueFromPipelineByPropertyName=$true)]            
   [Alias("CN", "ComputerName")]              
   [string]$computer="." ,            
               
   [string]$service="BITS" ,            
               
[parameter(Mandatory=$true)]            
   [string]$file            
               
)             
BEGIN {            
 if (!(Test-Path -Path $file)){Throw "log file not found"}            
}            
PROCESS {            
$result =  Get-WmiObject -Class Win32_Service -ComputerName $computer -Filter "Name='$service'"            
            
Write-Verbose "$($result.State)"            
            
if ($($result.State) -eq "Running"){            
  $logdata = "{0,14} {1} {2}" -f $computer, $($result.State), (get-date -Format f )            
}            
else{             
 $start = $result.StartService()             
 if ($start.ReturnValue -eq 0){            
   $logdata = "{0,14} {1} {2}" -f $computer, "Service Started", (get-date -Format f )            
 }            
 else {            
  $logdata = "{0,14} {1} {2}" -f $computer, "Service FAILED to Start", (get-date -Format f )            
 }              
}            
Add-Content -Path $file -Value $logdata             
}            
} ## end function

But I don’t like the answer for a number of reasons:

• end up out putting text
• log files involve extra work in parsing
• will other people know where the log file is

A better solution, in my mind, is to write the data to the event log.  In this case I would use the system log because we are testing services. The application log could be used or we could even create a specific event log for the purpose.

function test-service2{             
[CmdletBinding(SupportsShouldProcess=$true)]             
param (             
[parameter(Position=0,            
   ValueFromPipeline=$true,             
   ValueFromPipelineByPropertyName=$true)]            
   [Alias("CN", "ComputerName")]              
   [string]$computer="." ,            
               
   [string]$service="BITS"            
)             
PROCESS {            
$result =  Get-WmiObject -Class Win32_Service -ComputerName $computer -Filter "Name='$service'"            
            
Write-Verbose "$($result.State)"            
            
if ($($result.State) -eq "Running"){            
  $type = "Information"            
  $msg = "$computer - $service is $($result.State) "            
}            
else{             
 $start = $result.StartService()             
 if ($start.ReturnValue -eq 0){            
   $type = "Warning"            
   $msg = "$computer - $service  was started "            
 }            
 else {            
   $type = "Error"            
   $msg = "$computer - $service  FAILED to start"            
 }              
}            
Write-EventLog -LogName Application -Source ServiceTest -EntryType $type -Message $msg -EventId 9999            
            
}            
} ## end function

before using the function run this to create the event log source

New-EventLog -LogName Application -Source ServiceTest

The actions are all written to the event log as information, Warning or Error messages as appropriate.

Get-EventLog -LogName Application -Source ServiceTest

Shows the messages.

Enjoy