Sometimes while a powershell script is running you want to show a MessageBox with a information or warning to the user. In Windows Powershell no Commandlet exists to show a Message Box.

Nevertheless it is possible by using the .NET Windows.Forms.MessageBox class:-).

First of all load the assembly.

# Load assembly
[System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")

To show the messagebox call the static function show(“Message Text”)

$oReturn=[System.Windows.Forms.Messagebox]::Show("This is the Message text")

The function returned a value of enum System.Windows.Forms.DialogResult, that indicates which Button was pressed.
Possible Returncodes, depending on which button was pressed, are:

[system.enum]::getValues($oReturn.GetType())
None
OK
Cancel
Abort
Retry
Ignore
Yes
No

The default Button is the OK Button, there are further 5 combinations, see below.

[system.enum]::getNames([System.Windows.Forms.MessageBoxButtons])|foreach{[console]::Writeline("{0,20} {1,-40:D}",$_,[System.Windows.Forms.MessageBoxButtons]::$_.value__)}
                  OK 0
            OKCancel 1
    AbortRetryIgnore 2
         YesNoCancel 3
               YesNo 4
         RetryCancel 5

An Example, a Message box with an Ok and a Cancel button and a check which button was pressed:

$oReturn=[System.Windows.Forms.MessageBox]::Show("Message Text","Title",[System.Windows.Forms.MessageBoxButtons]::OKCancel)
switch ($oReturn){
	"OK" {
		write-host "You pressed OK"
		# Enter some code
	}
	"Cancel" {
		write-host "You pressed Cancel"
		# Enter some code
	}
}

Some examples

you can also use the number instead of the numeric constants to specify the buttons

[System.Windows.Forms.MessageBox]::Show("Message Text","Title",1)

This oneliner shows all possible Button combinations consecutively

[system.enum]::getValues([System.Windows.Forms.MessageBoxButtons])|foreach {[System.Windows.Forms.MessageBox]::Show("["+$_.GetType()+"]::"+$_.ToString(),"Message box Buttons",$_)}

You can style the message box with an icon, 4 are available

[system.enum]::getNames([System.Windows.Forms.MessageBoxIcon])|foreach{[console]::Writeline("{0,20} {1,-40:D}",$_,[System.Windows.Forms.MessageBoxIcon]::$_.value__)}
                None 0
                Hand 16
               Error 16
                Stop 16
            Question 32
         Exclamation 48
             Warning 48
            Asterisk 64
         Information 64

Example:

[System.Windows.Forms.MessageBox]::Show("Message Text","Title",[System.Windows.Forms.MessageBoxButtons]::OKCancel,[System.Windows.Forms.MessageBoxIcon]::Warning)

Same with numbers instead of numeric constants

[System.Windows.Forms.MessageBox]::Show("Message Text","Title",1,48)

the remaining…

 

All available icons consecutively

[system.enum]::getValues([System.Windows.Forms.MessageBoxIcon])|foreach {[System.Windows.Forms.Messagebox]::Show("["+$_.GetType()+"]::"+$_.ToString(),"Message box Icons",[System.Windows.Forms.MessageBoxButtons]::OK,$_)}

Michael