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

• Microsoft Access versions 1.0, 1.1, 2.0

SUMMARY

Moderate: Requires basic macro, coding, and interoperability skills.

This article describes and gives an example of how you can use the Shell() function in Access Basic to run intrinsic MS-DOS commands, such as Copy, Dir, Del, and so on.

This article assumes that you are familiar with Access Basic and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Access Basic, please refer to the "Building Applications" manual.

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

• 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.

REFERENCES

Microsoft Access "Building Applications," version 2.0, Chapter 5, "Access Basic Fundamentals," pages 113-132

Microsoft Access "Language Reference," version 2.0, "Shell Function," pages 568-569

For more information about the Shell() function, search for "Shell," and then "Shell Function" using the Microsoft Access Help menu.

For more information about using MS-DOS commands in Access Basic and on how to add additional functionality to these routines, please see the following article in the Microsoft Knowledge Base: