Recently, I was asked to make some changes to lots of users in Active Directory. For output, they wanted a log of everything that was changed and a log of where changes failed. Of course, I wanted a third log with verbose output of everything that was happening so, if need be, I could go back and fix anything.

Another thing I wanted to do was not write 5 times a second. Rather than slow down the process of making changes to users, I wanted to collect strings for the logs and write out every time I collected X number of strings.

To do this, I created a new Type using C# code. I’ve been reading Windows PowerShell for Developers (Dougals Finke) which has been an eye-opener to say the least.

Here is the code I came up with…

Add-type -TypeDefinition @"
using System.Collections;
public class Logger {
	public System.Collections.ArrayList Entries;
	public int    Count;
	public int    MaxLines;
	public string LogFile;

	public Logger(){
		Entries = new System.Collections.ArrayList();
		Count = 0;
		MaxLines = 5;
		LogFile = "";
	}

	public void Add(string str)
	{
		Entries.Add(str);
		Count++;
		if (Count >= MaxLines)
		{
			AppendLog();
		}
	}

	private void AppendLog()
	{
		if (! ([string]::isNullOrEmpty(LogFile)) )
		{
			using (System.IO.StreamWriter file = new System.IO.StreamWriter(LogFile, true))
			{
				foreach (string entry in Entries)
				{
					file.WriteLine(entry);
				}
			}
			Entries.Clear();
			Count = 0;
		}
	}

	public void Flush()
	{
		AppendLog();
	}

	public void setLogFile(string file)
	{
		LogFile = file;
	}

	public void setMaxLines(int max)
	{
		MaxLines = max;
	}
}
"@

This type compiles a “Logger” object which has a few properties and a few methods.

Logger Properties

Logger Methods

Example usage

PS C:\> $logger = new-object logger
PS C:\> $logger |ft -auto

Entries Count MaxLines LogFile
------- ----- -------- -------
{}          0        5


PS C:\> $logger.setMaxLines(10)
PS C:\> $logger |ft -auto

Entries Count MaxLines LogFile
------- ----- -------- -------
{}          0       10


PS C:\> (1..9) |% { $logger.Add("$_") }
PS C:\> $logger |ft -auto

Entries         Count MaxLines LogFile
-------         ----- -------- -------
{1, 2, 3, 4...}     9       10


PS C:\> $logger.setLogFile("C:\temp\log02.log")
PS C:\> $logger.Add("end")
PS C:\> $logger |ft -auto

Entries Count MaxLines LogFile
------- ----- -------- -------
{}          0       10 C:\temp\log02.log


PS C:\> gc $logger.LogFile
1
2
3
4
5
6
7
8
9
end
PS C:\>

Results

As a result of this, I was able to add this type to the script I was creating and create 3 logger objects:

# Debug logging
$logVerbose = new-object Logger
$logVerbose.setMaxLines(10)
$logVerbose.setLogFile("$pwd\Verbose.log")

# Change logging
$logChanges = new-object Logger
$logChanges.setMaxLines(5)
$logChanges.setLogFile("$pwd\Changes.log")

# Failed changes logging
$logFailedChanges = new-object Logger
$logFailedChanges.setMaxLines(5)
$logFailedChanges.setLogFile("$pwd\FailedChanges.log")

Logging to any one log was easy, just use the example above. If I wanted to log to all the logs, like setting the start point for the running of the script I would do something like this:

$commonLogString = (& $logPrefix ) + ""
$commonLogString += (& $logPrefix ) + "***********************`r`n"
$commonLogString += (& $logPrefix ) + "SCRIPT START`r`n"
$commonLogString += (& $logPrefix ) + "***********************`r`n"
$commonLogString += (& $logPrefix ) + "`r`n"
$commonLogString += (& $logPrefix ) + "Script Options:`r`n"
$commonLogString += (& $logPrefix ) + "-----------------------`r`n"
$commonLogString += (& $logPrefix ) + "Option 1: $Opt1`r`n"
$commonLogString += (& $logPrefix ) + "Option 2: $Opt2`r`n"
$commonLogString += (& $logPrefix ) + "Option 3: $Opt3`r`n"
$commonLogString += (& $logPrefix ) + "-----------------------`r`n"
#$commonLogString += (& $logPrefix ) + "`r`n"

$logVerbose.Add($commonLogString)
$logChanges.Add($commonLogString)
$logFailedChanges.Add($commonLogString)

The $logPrefix was a scriptblock I specified earlier on as

$logPrefix = {get-date -format "[ MM/dd/yy HH:mm:ss ] "}

This way each line would have a date/time header.