ACC: Using the Shell() Function to Run MS-DOS Commands

MORE INFORMATION

The Shell() function in Access Basic requires that you specify a file that has an extension of .EXE, .COM, .BAT or .PIF. These file types are registered as executable applications in the listed locations in the following operating environments:

   Windows 3.x and Windows for Workgroups 3.x
   ------------------------------------------
   Filename: WIN.INI
   Section: [windows]
   Item: Programs=com exe bat pif

   Windows NT 3.x
   ----------------------------------------------------------------------
   Filename: REGEDT32.EXE
   Registry Key:
   HKEY_CURRENT_USER\Software\Microsoft\WindowsNT\CurrentVersion\Windows
   Value: Programs
   Type: REG_SZ
   Item: com exe bat pif cmd
				

Using the Shell() function to run MS-DOS commands requires the use of the COMMAND.COM program. The COMMAND.COM program supports two optional parameters that you can use to run an intrinsic (or built in) MS-DOS function:

• COMMAND /C: This syntax runs a built in function, and then closes the MS-DOS session.
• COMMAND /K: This syntax runs a built in function and returns the MS-DOS command prompt.

Example

To create a sample application that demonstrates the use of these techniques, follow these steps:

1. Create a module and type the following line in the Declarations section:
   

         Option Explicit
   						

2. Type the following two functions:
   

         Function ShellDOS_Exit() As Integer
            On Local Error Goto ShellDOS_Exit_Err
            Dim MyCommand As String
            Dim TaskId As Integer
            ' Create command string to show the contents of current
            ' directory. Upon completion the window closes.
            MyCommand = "COMMAND.COM /C DIR /P"
            TaskId = Shell(MyCommand, 1)
            ShellDOS_Exit = True
         ShellDOS_Exit_End:
            Exit Function
         ShellDOS_Exit_Err:
            MsgBox Error$
            Resume ShellDOS_Exit_End
         End Function
   
         Function ShellDOS_Stay() As Integer
            On Local Error Goto ShellDOS_Stay_Err
            Dim MyCommand As String
            Dim TaskId As Integer
            ' Create command string to show the contents of current
            ' directory. Upon completion the window remain opens
            ' at the MS-DOS prompt.
            MyCommand = "COMMAND.COM /K DIR /P"
            TaskId = Shell(MyCommand, 1)
            ShellDOS_Stay = True
         ShellDOS_Stay_End:
            Exit Function
         ShellDOS_Stay_Err:
            MsgBox Error$
            Resume ShellDOS_Stay_End
         End Function
   						

3. To test the first function, type the following line in the Immediate window, and then press ENTER:
   
   ? ShellDOS_Exit()
   
   Note that the MS-DOS window displays the contents of the current directory (prompting you to press a key if the contents of the directory exceeds one display page) and returns True as a result of the function.
4. To test the second function, type the following line in the Immediate window, and then press ENTER:
   
   ? ShellDOS_Stay()
   
   Note that the MS-DOS window displays the contents of the current directory (prompting you to press a key if the contents of the directory exceeds one display page) and then keeps the MS-DOS session open and active, displaying the MS-DOS command prompt. The function also returns True as a result.