Write-Debug

Write-Debug
    [-Message] <String>
    [<CommonParameters>]

The Write-Debug cmdlet writes debug messages to the host from a script or command.

By default, debug messages are not displayed in the console, but you can display them by using the Debug parameter or the $DebugPreference variable.

This example writes a debug message.

Write-Debug "Cannot open file."

The default value of $DebugPreference is SilentlyContinue. Therefore, the message is not displayed in the console.

This example shows the effect of changing the value of the $DebugPreference variable. First, we display the current value of $DebugPreference and attempt to write a debug message. Then we change the value of $DebugPreference to Continue, which allows debug messages to be displayed.

PS> $DebugPreference
SilentlyContinue
PS> Write-Debug "Cannot open file."
PS>
PS> $DebugPreference = "Continue"
PS> Write-Debug "Cannot open file."
DEBUG: Cannot open file.

For more information about $DebugPreference, see about_Preference_Variables.

The Test-Debug function writes the value of the $DebugPreference variable to the PowerShell host and to the Debug stream. In this example, we use the Debug parameter to override the $DebugPreference value.

function Test-Debug {
    [CmdletBinding()]
    param()
    Write-Debug ('$DebugPreference is ' + $DebugPreference)
    Write-Host ('$DebugPreference is ' + $DebugPreference)
}

PS> Test-Debug
$DebugPreference is SilentlyContinue

PS> Test-Debug -Debug
DEBUG: $DebugPreference is Continue
$DebugPreference is Continue
PS> $DebugPreference
SilentlyContinue

Notice that the value of $DebugPreference changes when you use the Debug parameter. This change only affects the scope of the function. The value is not affected outside the function.

For more information about the Debug common parameter, see about_CommonParameters.

This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable, -InformationAction, -InformationVariable, -OutBuffer, -OutVariable, -PipelineVariable, -ProgressAction, -Verbose, -WarningAction, and -WarningVariable. For more information, see about_CommonParameters.

You can pipe a string that contains a debug message to this cmdlet.

This cmdlet returns no output. It only writes to the debug stream.