Script Tips

Valid Case for Arguments

Use arguments to dictate variables when calling a script.

• By Bob Kelly
• 05/21/2007

Establishing variables for certain things just makes good sense. If there is a path to a file or directory, that's a perfect candidate for a variable. That way, the code can be easily changed in the future or can be reused in another script. Sometimes you may even set a variable to easily change the behavior of your script, such as if your script should display information or not, if it should take actions or just display what it would do for testing purposes. I'm sure you can think of many other such "yes or no" type options you may want to control when you run the script.

If you want to change these values frequently or if you'll be sharing this script for others to execute, constantly editing these values in the code may not be desirable. This is where arguments become a valuable feature.

By handling arguments, your script can function much as a command line tool. Whatever options your script provides may be handled by these parameters as you dictate in your code.

The Windows Script host supports arguments as property values where you may check how many arguments have been passed to your script and what text each contains. A space is the delimiter that separates parameters, not the common dash or slash characters used to identify command line parameters (you can require or simply ignore such identifiers if you wish). How you want to handle arguments will depend very much on your script and what it does.

If you make use of arguments today you know how valuable they can be. If you've never worked with arguments before, here's a skeleton that's aimed at showing you how to easily take advantage of them in your scripts:

If WScript.arguments.count = 0 Then
   Exit Do
End If

For i = 0 To (WScript.arguments.count - 1)
sCurrentArgument = WScript.Arguments.Item(i)
Select Case (UCase(sCurrentArgument)
   Case "/A", "-A"
      optionA = True
   Case "/B", "-B"
      optionB = True
   Case "/C", "-C"
      optionC = True
   Case Else
      WScript.Echo "Invalid Argument Passed: " &_
         sCurrentArgument & ". Aborting."
      WScript.Quit
   End Select
Next

If optionA Then WScript.Echo "Do actions for option A." End If
If optionB Then WScript.Echo "Do actions for option B." End If
If optionC Then WScript.Echo "Do actions for option C." End If

Tech Help—Just An E-Mail Away Got a Windows, Exchange or virtualization question or need troubleshooting help? Or maybe you want a better explanation than provided in the manuals? Describe your dilemma in an e-mail to the MCPmag.com editors at [email protected]; the best questions get answered in this column and garner the questioner with a nifty Redmond T-shirt. When you send your questions, please include your full first and last name, location, certifications (if any) with your message. (If you prefer to remain anonymous, specify this in your message, but submit the requested information for verification purposes.)

This script lets you know if an A, B or C switch is passed upon execution. Using this same code and logic, you should be able to easily implement command line arguments in your scripts. Try it out!