by Adam Murray (4 Submissions)
Category: Windows API Call/Explanation
Compatability: Visual Basic 3.0
Difficulty: Advanced
Date Added: Wed 3rd February 2021
Rating: 
(4 Votes)
Executes a command passed as a string, and waits for it to finish. Example: lResult = ShellAndWait("d:\ztbold\ztw.exe", 10000)
That calls the d:\ztbold\ztw.exe and waits for it to exit for up to 10,000 milliseconds.
If you want to call something and redirect its output to a file, you'll have to call CMD.EXE like this:
lResult = ShellAndWait("cmd.exe /c MyCommand.EXE > MyFile.TMP", 10000)
Inputs
strCommandLine As String: the command line to execute;
lWait As Long: the number of milliseconds to wait for the process to finish, or 0 to wait indefinately
Assumes
This code is not original; I am not its author. I believe it was originally available as an MSDN KB article.
Code Returns
Application return code on Success, -1 on Error
Side Effects
None.
API DeclarationsPrivate Declare Function CreateProcess Lib "kernel32" Alias "CreateProcessA" (ByVal lpApplicationName As Long, ByVal lpCommandLine As String, ByVal lpProcessAttributes As Long, ByVal lpThreadAttributes As Long, ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long, ByVal lpEnvironment As Long, ByVal lpCurrentDriectory As Long, lpStartupInfo As STARTUPINFO, lpProcessInformation As PROCESS_INFORMATION) As Long
Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal hHandle As Long, ByVal dwMilliseconds As Long) As Long
Private Type PROCESS_INFORMATION
hProcess As Long
hThread As Long
dwProcessId As Long
dwThreadId As Long
End Type
Private Type STARTUPINFO
cb As Long
lpReserved As Long
lpDesktop As Long
lpTitle As Long
dwX As Long
dwY As Long
dwXSize As Long
dwYSize As Long
dwXCountChars As Long
dwYCountChars As Long
dwFillAttribute As Long
dwFlags As Long
wShowWindow As Integer
cbReserved2 As Integer
lpReserved2 As Long
hStdInput As Long
hStdOutput As Long
hStdError As Long
End Type
Private Declare Function TerminateProcess Lib "kernel32" (ByVal hProcess As Long, ByVal uExitCode As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function GetExitCodeProcess Lib "kernel32" (ByVal hProcess As Long, lpExitCode As Long) As Long
VBcodersFunction ShellAndWait(strCommandLine As String, lWait As Long) As Long
Dim objProcess As PROCESS_INFORMATION
Dim objStartup As STARTUPINFO
Dim lResult As Long
Dim lExitCode As Long
objStartup.cb = 68
objStartup.lpReserved = 0
objStartup.lpDesktop = 0
objStartup.lpTitle = 0
objStartup.dwX = 0
objStartup.dwY = 0
objStartup.dwXSize = 0
objStartup.dwYSize = 0
objStartup.dwXCountChars = 0
objStartup.dwYCountChars = 0
objStartup.dwFillAttribute = 0
objStartup.dwFlags = 0
objStartup.wShowWindow = 0
objStartup.cbReserved2 = 0
objStartup.lpReserved2 = 0
objStartup.hStdInput = 0
objStartup.hStdOutput = 0
objStartup.hStdError = 0
'try and Create the process
lResult = CreateProcess(0, strCommandLine, 0, 0, 0, 0, 0, 0, objStartup, objProcess)
If lResult = 0 Then
ShellAndWait = -1
Exit Function
End If
'now, wait on the process
If lWait <> 0 Then
lResult = WaitForSingleObject(objProcess.hProcess, lWait)
If lResult = 258 Then 'did we timeout?
lResult = TerminateProcess(objProcess.hProcess, -1)
lResult = WaitForSingleObject(objProcess.hProcess, lWait)
End If
End If
'let's get the exit code from the process
lResult = GetExitCodeProcess(objProcess.hProcess, lExitCode)
lResult = CloseHandle(objProcess.hProcess)
lResult = CloseHandle(objProcess.hThread)
ShellAndWait = lExitCode
End Function