Write-Log.ps1
Description
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@BanterBoy: - Explain what the script does and why it is useful.
@GitHub Copilot - The code is a PowerShell function called Write-Log. It is designed to add logging capability to other scripts. The function writes a message to a specified log file with the current time stamp. In addition to writing output and/or verbose, you can write to a log file for later debugging. The function has several parameters that allow you to customize the log message.
The Message parameter is the content that you wish to add to the log file. The Path parameter is the path to the log file to which you would like to write. By default, the function will create the path and file if it does not exist. The Level parameter specifies the criticality of the log information being written to the log (i.e. Error, Warning, Informational). The NoClobber parameter is used if you do not wish to overwrite an existing file.
The function has several examples that demonstrate how to use it. For example, you can use the Write-Log function to write a message to a log file with the default path and file name. You can also specify a custom path and file name. Additionally, you can specify the level of the log message (i.e. Error, Warning, Informational).
The function uses PowerShell’s switch statement to write the log message to the appropriate pipeline (i.e. Error, Warning, Informational). The log message is formatted with the current date and time stamp, the level of the log message, and the message itself. The log message is then written to the specified log file.
To improve the code’s readability, the function uses descriptive parameter names and comments to explain what each section of the code does. Additionally, the function uses PowerShell’s cmdlet binding attribute to enable advanced parameter validation and pipeline support. Finally, the function uses PowerShell’s verbose preference to display verbose messages.
To improve the code’s performance, the function could be optimized to handle large log files more efficiently. For example, the function could use a buffered approach to write log messages to the log file. Additionally, the function could use a more efficient date and time stamp format.
@BanterBoy: -Can you provide an example of how to use the Write-Log function in a PowerShell script?
@GitHub Copilot - Certainly! Here’s an example of how to use the Write-Log function in a PowerShell script:
# Import the Write-Log function
. .\Write-Log.ps1
# Write a message to the log file
Write-Log -Message "Starting script" -Path "C:\Logs\Script.log"
# Do some work here...
# Write another message to the log file
Write-Log -Message "Script completed successfully" -Path "C:\Logs\Script.log"
In this example, we first import the Write-Log function into our script. We then use the function to write a message to the log file at the beginning of our script, and another message at the end of our script. The -Message
parameter specifies the content of the log message, and the -Path
parameter specifies the path to the log file.
You can also use the -Level
parameter to specify the criticality of the log message (i.e. Error, Warning, Informational). For example:
# Write an error message to the log file
Write-Log -Message "An error occurred" -Path "C:\Logs\Script.log" -Level Error
This will write an error message to the log file and also write the message to the error pipeline.
Script
<#
.Synopsis
Write-Log writes a message to a specified log file with the current time stamp.
.DESCRIPTION
The Write-Log function is designed to add logging capability to other scripts.
In addition to writing output and/or verbose you can write to a log file for
later debugging.
.NOTES
Created by: Jason Wasser @wasserja
Modified: 11/24/2015 09:30:19 AM
Changelog:
* Code simplification and clarification - thanks to @juneb_get_help
* Added documentation.
* Renamed LogPath parameter to Path to keep it standard - thanks to @JeffHicks
* Revised the Force switch to work as it should - thanks to @JeffHicks
To Do:
* Add error handling if trying to create a log file in a inaccessible location.
* Add ability to write $Message to $Verbose or $Error pipelines to eliminate
duplicates.
.PARAMETER Message
Message is the content that you wish to add to the log file.
.PARAMETER Path
The path to the log file to which you would like to write. By default the function will
create the path and file if it does not exist.
.PARAMETER Level
Specify the criticality of the log information being written to the log (i.e. Error, Warning, Informational)
.PARAMETER NoClobber
Use NoClobber if you do not wish to overwrite an existing file.
.EXAMPLE
Write-Log -Message 'Log message'
Writes the message to c:\Logs\PowerShellLog.log.
.EXAMPLE
Write-Log -Message 'Restarting Server.' -Path c:\Logs\Scriptoutput.log
Writes the content to the specified log file and creates the path and file specified.
.EXAMPLE
Write-Log -Message 'Folder does not exist.' -Path c:\Logs\Script.log -Level Error
Writes the message to the specified log file as an error message, and writes the message to the error pipeline.
.LINK
https://gallery.technet.microsoft.com/scriptcenter/Write-Log-PowerShell-999c32d0
#>
function Write-Log {
[CmdletBinding()]
Param
(
[Parameter(Mandatory = $true,
ValueFromPipelineByPropertyName = $true)]
[ValidateNotNullOrEmpty()]
[Alias("LogContent")]
[string]$Message,
[Parameter(Mandatory = $false)]
[Alias('LogPath')]
[string]$Path = 'C:\Logs\PowerShellLog.log',
[Parameter(Mandatory = $false)]
[ValidateSet("Error", "Warn", "Info")]
[string]$Level = "Info",
[Parameter(Mandatory = $false)]
[switch]$NoClobber
)
Begin {
# Set VerbosePreference to Continue so that verbose messages are displayed.
$VerbosePreference = 'Continue'
}
Process {
# If the file already exists and NoClobber was specified, do not write to the log.
if ((Test-Path $Path) -AND $NoClobber) {
Write-Error "Log file $Path already exists, and you specified NoClobber. Either delete the file or specify a different name."
Return
}
# If attempting to write to a log file in a folder/path that doesn't exist create the file including the path.
elseif (!(Test-Path $Path)) {
Write-Verbose "Creating $Path."
$NewLogFile = New-Item $Path -Force -ItemType File
}
else {
# Nothing to see here yet.
}
# Format Date for our Log File
$FormattedDate = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
# Write message to error, warning, or verbose pipeline and specify $LevelText
switch ($Level) {
'Error' {
Write-Error $Message
$LevelText = 'ERROR:'
}
'Warn' {
Write-Warning $Message
$LevelText = 'WARNING:'
}
'Info' {
Write-Verbose $Message
$LevelText = 'INFO:'
}
}
# Write log entry to $Path
"$FormattedDate $LevelText $Message" | Out-File -FilePath $Path -Append
}
End {
}
}
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