VBA Shell Function

The VBA Shell function is a built-in function that allows you to run other applications or executable from within your VBA code. It is a handy tool for automating tasks that require the use of external programs.

VBA Shell Function – Purpose, Syntax and Arguments

Purpose

The main purpose of the Shell function is to launch external applications from within VBA code. This can be useful for automating tasks that require the use of other programs, such as data extraction, report generation, or file manipulation.

Syntax

Shell(pathname[,windowstyle])

Arguments

• pathname: This is a required argument that specifies the path and name of the application or executable file that you want to run.
• windowstyle: This is an optional argument that specifies the appearance of the application window when it is opened. The default value is 1, which opens the application in a normal window. Other possible values are 0 (hides the window), 2 (minimizes the window), 3 (maximizes the window), and 4 (opens the window as an MDI child).

Example

Let’s say you have a VBA program that downloads a report from a website and saves it as a text file. You want to open this text file in Notepad after it has been saved. You can use the Shell function to achieve this:

Dim reportPath as String
reportPath = "C:\Users\username\Documents\Report.txt"
Shell "C:\Windows\System32
otepad.exe " & reportPath

In this example, we first declare a string variable called ‘reportPath’ and assign it the path of our saved text file. Then, we use the Shell function to open Notepad and pass the report path as an argument. This will open the Notepad application and load the report file for viewing.

Remarks and Important Notes

• The Shell function is only compatible with the Windows operating system. It will not work on Mac or other platforms.
• The path specified in the ‘pathname’ argument must be enclosed in double quotation marks.
• The path can be a full path or a relative path, as long as it can be recognized by the Windows operating system.
• The Shell function can also be used to run batch files or script files, such as .bat, .cmd, .vbs, and .js files.
• If the application or file path contains spaces, you may need to use the Chr(34) function to enclose it in double quotation marks within the VBA code. For example:

  Shell Chr(34) & "C:\Program Files\MyApp\MyProgram.exe" & Chr(34)

The Shell function is a powerful tool for automating tasks that require the use of external applications or executables in VBA code. It is an efficient way to launch programs and perform tasks without leaving the VBA environment.

Understanding VBA Shell Function with Examples

Example 1: Running an External Program using Shell Function

Description: The Shell function in Visual Basic for Applications (VBA) is used to execute an external program or a Windows command from within VBA. This allows the user to control and automate other programs through their VBA code. The Shell function returns the process ID (PID) of the launched program, which can then be used to manipulate the program further if needed.

Code:

Sub RunExternalProgram()
    'Launches the Notepad program using the Shell function.
    Dim processID As Double
    processID = Shell("C:\Windows\System32
otepad.exe", vbNormalFocus)
    'Shows a message box with the process ID of the Notepad program.
    MsgBox "Notepad process ID: " & processID
    
End Sub

1. The first line of code declares a Sub procedure named RunExternalProgram.
2. In the second line, the processID variable is declared as a Double data type. This variable will hold the PID of the launched program.
3. The Shell function is then used in the third line to execute the Notepad program. The first argument is the path to the program, in this case, it is the location of the Notepad executable file. The second argument, vbNormalFocus, specifies how the launched program will appear on the screen.
4. In the fourth line, a MsgBox function is used to display a message box with the process ID of the Notepad program. The & symbol is used to concatenate the string and the processID variable.
5. The End Sub statement marks the end of the procedure.

Explanation: The Shell function in this example is used to open the Notepad program, as specified by the path in the first argument. The vbNormalFocus argument tells the function to open the program with the normal focus, which means it will appear in the foreground of the screen. The process ID of the launched program is then returned by the Shell function and stored in the processID variable. The process ID is a unique identifier for a program and can be used to manipulate the program in various ways. In this example, the process ID is displayed in a message box using the MsgBox function.

Example 2: Opening a File Using Shell Function

Description: The Shell function can also be used to open a specific file using its default program. For example, if a user wants to open a Word document, they can use the Shell function to launch the document in Microsoft Word.

Code:

Sub OpenFile()
    'Opens a Word document using the Shell function.
    Dim documentPath As String
    documentPath = "C:\Users\username\Documents\Sample.docx"
    Shell "explorer """ & documentPath & """"
    
End Sub

1. The first line of code declares a Sub procedure named OpenFile.
2. In the second line, the documentPath variable is declared as a String data type. This variable will contain the path of the document to be opened.
3. The path of the document is specified in the third line, in this example, it is a Word document located in the Documents folder.
4. The Shell function is then used in the fourth line to open the file’s default program, in this case, Microsoft Word. The explorer command is used to open a file explorer window, and the file path is enclosed within double quotation marks, as shown in the code. This is done to handle any spaces in the file path.
5. The End Sub statement marks the end of the procedure.

Explanation: In this example, the Shell function is used to open a specific document in its default program. The document path is specified in the documentPath variable and is then passed as an argument to the Shell function. This will open the document using its default program, which is Word in this case.

Example 3: Launching Multiple Programs Using Shell Function

Description: The Shell function allows the user to launch more than one program at a time. This can be useful for automating tasks that require multiple programs to be opened sequentially.

Code:

Sub LaunchMultiplePrograms()
    'Launches multiple programs using the Shell function.
    Dim pid1 As Double
    Dim pid2 As Double
    
    'Launches the Notepad program.
    pid1 = Shell("C:\Windows\System32
otepad.exe", vbNormalFocus)
    
    'Launches the Calculator program.
    pid2 = Shell("C:\Windows\System32\calc.exe", vbNormalFocus)
    
    'Shows a message box with the process IDs of both programs.
    MsgBox "Notepad process ID: " & pid1 & vbCrLf & "Calculator process ID: " & pid2
    
End Sub

1. The first line of code declares a Sub procedure named LaunchMultiplePrograms.
2. In the third and fourth lines, the pid1 and pid2 variables are declared as Double data types. These variables will hold the PIDs of the launched programs.
3. The Shell function is then used twice, in lines 7 and 11, to launch the Notepad and Calculator programs.
4. In line 15, a MsgBox function is used to display a message box with the process IDs of both programs. The & vbCrLf & symbol is used to add a line break between the two process IDs.
5. The End Sub statement marks the end of the procedure.

Explanation: This example demonstrates how the Shell function can be used to launch multiple programs one after the other. The pid1 and pid2 variables are used to store the PIDs of the launched programs, and this information can be used later to manipulate the programs if needed. In this example, a message box is displayed with the process IDs of both launched programs using the MsgBox function.

Example 4: Specifying the Window State using Shell Function

Description: By default, the Shell function launches a program in the foreground with normal focus. However, the user can specify the window state of the launched program. This means that the program can be launched minimized, maximized, or hidden from the user.

Code:

Sub SpecifyWindowState()
    'Launches the Notepad program as hidden using the Shell function.
    Dim processID As Double
    processID = Shell("C:\Windows\System32
otepad.exe", vbHide)
    
End Sub

1. The first line of code declares a Sub procedure named SpecifyWindowState.
2. In the third line, the processID variable is declared as a Double data type.
3. The Shell function is used to open the Notepad program in line 6. The second argument, vbHide, specifies that the program should be launched in a hidden state. This means that the user will not be able to see the program, but it will still be running in the background. The process ID of the launched program is returned by the Shell function and stored in the processID variable.
4. The End Sub statement marks the end of the procedure.

Explanation: In this example, the Shell function is used to open the Notepad program in a hidden state. This can be useful for background tasks that do not require user interaction. The vbHide argument specifies the program’s window state, and the process ID of the launched program is stored in the processID variable.

Example 5: Running a Batch File Using the Shell Function

The Shell function can be used to run batch files (.bat) from within VBA code. This is useful when you need to automate tasks that involve executing a sequence of commands in a batch file, such as file management or system maintenance tasks.

Code:

Sub RunBatchFile()

'Launches a batch file to delete temporary files using the Shell function.
Dim batchFilePath As String
batchFilePath = "C:\Scripts\CleanTempFiles.bat"
Shell batchFilePath, vbNormalFocus

End Sub

How this works:

1. In this example, a batch file located at “C:\Scripts\CleanTempFiles.bat” is executed using the Shell function.
2. The Shell function takes the path of the batch file as its argument. The second argument, vbNormalFocus, specifies that the batch file should run with normal window focus.
3. The batch file might contain commands to delete temporary files or run any other system commands that can be handled by a batch file.
4. When this code is run, the batch file will execute, performing its predefined tasks, such as cleaning temporary files, and display the result in a normal window.

Explanation: The Shell function in this example demonstrates how you can use it to run external scripts, such as batch files, directly from your VBA code. This opens up many possibilities for automating file and system management tasks within VBA.

Conclusion

The Shell function is a powerful tool in VBA that allows the user to control and automate other programs from within their VBA code. This function can be used to launch external programs, open files, specify the window state of the launched program, assign a custom window title, and open multiple programs sequentially. Understanding the Shell function and how it can be used in different scenarios can greatly enhance a user’s ability to automate tasks in VBA.