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Preventing multiple instances of a VB EXE from running?

Posted on 2001-06-13
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Last Modified: 2012-05-04
I have a VB app that is delivered in the form of an EXE file.  I must prevent the user from running multiple instances of this program.  How do I do this?
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Question by:david749
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beckingh earned 50 total points
ID: 6185837
If App.PrevInstance = True Then
        MsgBox "There are two instances of the application running.  Please click OK, wait 10 seconds, and restart the application.  If the problem persists contact your System Administrator.", vbOKOnly, csMsgBoxTitle
        GoTo exitsub
    End If
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by:beckingh
ID: 6185844
Obviously only the "If App.PrevInstance = True Then" part is relevant :)
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by:beckingh
ID: 6185858
Here's a nice link to a way of launching the app that is already running.

http://vbcode.com/asp/showsn.asp?theID=574
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Expert Comment

by:Richie_Simonetti
ID: 6187559
One way to do it is adding a module to your project, create a sub Main procedure and:

Sub Main
    If app.previnstance then
       end
    else
       frmMain.show
    end if
End Sub

Don't forget to swith your start object to the sub main routine going to Project properties menu.
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