Using Environment variables inside a VBScript script

Jerry Lees — Fri, 24 Oct 2008 00:30:03 +0000

As an extension of the theme I’ve been blogging about lately of “interfacing with other types of applications” in VBScript, I’d like to share with you a snippet of VBScript code that will allow you to read environment variables from your system. This will allow you to determine a great deal of information, since many applications use environment variables for configuration information– and the OS itself does as well, like the server that logged you on is %logonserver%.

There are two types of environment variables:

System variables, which are available to every process across the system
Process variables, which are only available to the process and disappear when the process is completed. These are sometimes referred to a user environment variables.

You can see examples of each of these environment variables being used below via the “Environment” method of the Wscript.Shell object.
Set WshShell = WScript.CreateObject(“WScript.Shell”)

‘create a Process (user profile) Level environment variable object
Set WshProccessEnv = WshShell.Environment(“Process”)
‘create a System Level environment variable object
Set WshSysEnv = WshShell.Environment(“System”)

‘display a system environment variable
Wscript.Echo WshSysEnv(“NUMBER_OF_PROCESSORS”)
‘display a user profile level environment variable
Wscript.Echo WsProcessEnv(“Path”)

Enjoy!

Communicating error levels to a calling application from with in VBScript

Jerry Lees — Fri, 17 Oct 2008 23:11:30 +0000

We’ve discussed error handling previously (via the On Error Goto 0 command) in a entry titled, Using error control in a VBScript to recover from odd errors. However, occasionally you need to communicate a condition back to an application or batch file that calls a script as part of its processing. One reason you may need to do this is if you need to call a separate script or application depending on the outcome of the script. You can do this with what is called an error level. Keep in mind this may not have anything to do with an error in the script but can, instead, be used as a method to control how another applicatioin responds to a particular condition.

For example, say you already have a executable that processes a file into a database– but you don’t want to run the executable on a old file because it would cause all sorts of duplicated entries in the database. you might not be able to go back to the person who wrote the executable and have them change it or the executable might not have even been written by the company where you work! You could, however write a script to check the date of a file and if it was created during a time frame return a error level back to a batch file that calls your script and preforms the logic to decide if the executable needed to be ran. Take this batch file for example:

Echo off
cscript Yourscript.vbs
If %errorlevel% == 3 goto runexe
Echo “File to old”
goto EndBatch
:runexe
processingprogram.exe
:EndBatch

This would only run the executable IF your script returned a error level of 3! So you can then preform work and checks never intended by the executable when it was written only if the conditions are correct for it to run.

The line of code in VBScript you would add to your script to communicate back to the batch file would be:

WScript.quit(3)

This will return a error level of 3 back to the batch file and cause the batch file to THEN run your executable.

So, there you have it! A quick and simple method to extend the life of those aging processes that work fine– just need a minor tweak because your environment has changed.

The VBScript Network and Systems Administrator's Cafe » wscript

Using Environment variables inside a VBScript script

Communicating error levels to a calling application from with in VBScript