WD2000: Shell Command Does Not Wait for Application to Finish (212547)

MORE INFORMATION

Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements. Visual Basic for Applications processes macro commands asynchronously. This means that each command runs independently of any timing process, such as a clock.

Because macros do not wait for the started program to finish before running the next command, this can cause problems, particularly if subsequent commands rely on results from the started program.

This Visual Basic for Applications macro sample uses a combination of a Do Loop with the Exists method to determine whether the started program is still running.

Sub IsTaskRunning()
   ' If file does not exist, GoTo error trap.
   On Error GoTo itrErrTrap
   ' Run sample batch file in MS-DOS window.
   Shell "c:\test.bat"
   Do
      ' Note: When specifying the Application name
      ' with the Exists(Name) argument, omit the
      ' Application extension.
      test = Tasks.Exists("test")
   Loop Until  test = 0
   MsgBox "The application has quit."
itrErrTrap: ' Note: This line must be left aligned.
   If Err > 0 then MsgBox Err.Description
End Sub
				

For more information about the Exists method, in the Visual Basic Editor, click Microsoft Visual Basic Help on the Help menu, type Exists method in the Office Assistant or the Answer Wizard, and then click Search to view the topic.

For more information about how to use the sample code in this article, click the article number below to view the article in the Microsoft Knowledge Base: