Microsoft KB Archive/147806

= How to Use ExitWindowsExec in VB to Run MS-DOS Batch File =

Article ID: 147806

Article Last Modified on 1/8/2003

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APPLIES TO


 * Microsoft Visual Basic 4.0 Professional Edition
 * Microsoft Visual Basic 4.0 16-bit Enterprise Edition

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This article was previously published under Q147806



SUMMARY
The ExitWindowsExec function terminates Windows, runs a specified MS-DOS application, and then restarts Windows. The information in this article shows you how to call this function from Microsoft Visual Basic.



MORE INFORMATION
The ExitWindowsExec function is typically used by installation programs to replace components of Windows that are active when Windows is running. Normally, you'd want to run an MS-DOS batch file that performs the file copying while Windows is temporarily shut down. The declaration for ExitWindowsExec is as follows:

' Place the following declaration on one, single line:

Private Declare Function ExitWindowsExec Lib "User" (ByVal lpszExe As String,     ByVal lpszParams As Any) As Integer

First Parameter: lpszExe$
The first parameter for ExitWindowsExec, lpszExe$, should be a string containing the fully qualified path to the executable file you want to run. This string must contain no more than 127 characters. For batch files, you'll need to specify COMMAND.COM as the file -- C:\DOS\COMMAND.COM. To get the fully qualified path in Visual Basic to COMMAND.COM, you can use the Environ$ function:

lpszExe$ = Environ$("COMSPEC")

For more information on the Environ$ function, please refer to the Microsoft Visual Basic Language Reference or the Help menu.

Second Parameter: lpszParams$
The second parameter for ExitWindowsExec, lpszParams$, should be a string containing any necessary parameters for the executable file. If no parameters are necessary, pass a long integer 0 such as 0&.

To execute a batch file, however, this is where you specify the path to the batch file and any parameters it needs. Also, you need to preface the string with the /c switch which tells MS-DOS to invoke a copy of COMMAND.COM. Here is an example:

lpszParams$ = "/C C:\DIRNAME\GENERIC.BAT PARAMETER1 PARAMETER2"

The return value of this function is False when the function fails.

Step-by-Step Example
  Using either NotePad in Windows or Edit in MS-DOS, create a batch file in the root directory of your hard disk called C:\RUNIT.BAT. Give it the following contents: @echo off echo Making Backup of autoexec.bat copy c:\autoexec.bat c:\*.bak echo Done

 Start a new project in Visual Basic (Alt, F, N). Form1 is created by default.  Add the following declaration to the General Declarations section of the form: ' Place the following declaration on one, single line:

Private Declare Function ExitWindowsExec Lib "User" (ByVal lpszExe As String, _     ByVal lpszParams As Any) As Integer

  Add a command button (Command1) to the form, and place the following code in the Click event. Private Sub Command1_Click sComspec$ = Environ$("COMSPEC") ret% = ExitWindowsExec(sComspec$, "/c c:\runit.bat") End Sub

 Save the project (Alt, F, V). Then press the F5 key to run the program. Click the command button to exit Windows, run the batch file, and then restart Windows.

Additional query words: vbwin vb416 4.00

Keywords: kbwndw KB147806

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