Knowing when a Shell task is finished?
I'm trying to find a reliable way to know when a Shell task has finished.
From the KB article # Q127030:
"The Shell function in Microsoft Visual Basic is used to execute an application. Often, it is useful to get a Window handle (hWnd) to the application so you can manipulate it using the Windows APIs. Unfortunately, the Shell function returns an Instance handle (hInstance), which is different from a Window handle. This article shows by example how to use the GetWinHandle() function to return a Window handle based on an Instance handle."
Is this transformation necessary for what I'm doing? Do I need to transform it to a Windows handle to know when the Shell task has finished?
Specifically, what I do is to use two command line programs sequentially -- the output of the first program is the input of the other. The problem is that VB just keeps on running, so the second Shell function starts before the file is ready!
I was previously recommended using the CreateProcess API function instead of Shell. I remember I tried and I remember I wasn't successful, but I don't remember why. I hope transforming the Instance handle to a Windows handle and wait for the handle to terminate is an alternative solution. What do you think?
The most convincing suggestion wins. :-)
From the KB article # Q127030:
"The Shell function in Microsoft Visual Basic is used to execute an application. Often, it is useful to get a Window handle (hWnd) to the application so you can manipulate it using the Windows APIs. Unfortunately, the Shell function returns an Instance handle (hInstance), which is different from a Window handle. This article shows by example how to use the GetWinHandle() function to return a Window handle based on an Instance handle."
Is this transformation necessary for what I'm doing? Do I need to transform it to a Windows handle to know when the Shell task has finished?
Specifically, what I do is to use two command line programs sequentially -- the output of the first program is the input of the other. The problem is that VB just keeps on running, so the second Shell function starts before the file is ready!
I was previously recommended using the CreateProcess API function instead of Shell. I remember I tried and I remember I wasn't successful, but I don't remember why. I hope transforming the Instance handle to a Windows handle and wait for the handle to terminate is an alternative solution. What do you think?
The most convincing suggestion wins. :-)
Another example from MS:
"HOWTO: 32-Bit App Can Determine When a Shelled Process Ends (Q129796)"
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q129796&GSSNB=1
"HOWTO: 32-Bit App Can Determine When a Shelled Process Ends (Q129796)"
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q129796&GSSNB=1
Listioning......
The above suggestions are about "How to sleep and wait a process to terminate".
Any help for " When I need to know, how to check if a process is finished"?
The above suggestions are about "How to sleep and wait a process to terminate".
Any help for " When I need to know, how to check if a process is finished"?
ASKER CERTIFIED SOLUTION
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Hi!
Here's a file for you over the ent:
Download...
http://www.vb-helper.com/HowTo/runwait.zip
Description: Start another program and wait until it finishes (2K)
That's it!
glass cookie : )
Here's a file for you over the ent:
Download...
http://www.vb-helper.com/HowTo/runwait.zip
Description: Start another program and wait until it finishes (2K)
That's it!
glass cookie : )
Dim lPid As Long
Dim lHnd As Long
Dim lRet As Long
If Trim$(txtApp) = "" Then Exit Sub
lPid = Shell(txtApp.Text, vbNormalFocus)
If lPid <> 0 Then
'Get a handle to the shelled process.
lHnd = OpenProcess(SYNCHRONIZE, 0, lPid)
'If successful, wait for the application to end and close the handle.
If lHnd <> 0 Then
lRet = WaitForSingleObject(lHnd, INFINITE)
CloseHandle (lHnd)
End If
MsgBox "Just terminated.", vbInformation, "Shelled Application"
End If
This code component is available at: http://www.thescarms.com/vbasic/wait.asp
Dim lHnd As Long
Dim lRet As Long
If Trim$(txtApp) = "" Then Exit Sub
lPid = Shell(txtApp.Text, vbNormalFocus)
If lPid <> 0 Then
'Get a handle to the shelled process.
lHnd = OpenProcess(SYNCHRONIZE, 0, lPid)
'If successful, wait for the application to end and close the handle.
If lHnd <> 0 Then
lRet = WaitForSingleObject(lHnd, INFINITE)
CloseHandle (lHnd)
End If
MsgBox "Just terminated.", vbInformation, "Shelled Application"
End If
This code component is available at: http://www.thescarms.com/vbasic/wait.asp
ASKER
Yes, it works! But I got a new problem, which will be the material for next question.
"Wait for a Process to Terminate"
http://www.thescarms.com/vbasic/wait.asp