How do I Launch OpenFiles.exe from Delphi XE2 ShellExecute? - delphi

Question

I need to launch MS Window's OpenFiles.exe from a Delphi XE2 application to export currently opened files to a text file. The normal cmd.exe syntax is something like:
Openfiles.exe /query /s 127.0.0.1 /nh >c:\OpenFilesExport.txt
Using the following code returns a successful exit code but the export file is not generated:
var
exInfo: TShellExecuteInfo;
exitcode: DWORD;
begin
FillChar(exInfo, Sizeof(exInfo), 0);
with exInfo do
begin
cbSize := Sizeof(exInfo);
fMask := SEE_MASK_NOCLOSEPROCESS or SEE_MASK_FLAG_DDEWAIT;
lpVerb := 'open';
lpFile := Pchar('Openfiles.exe');
lpParameters := PChar('/query /s 127.0.0.1 /nh >c:\OpenFilesOutput.txt');
nShow := SW_SHOWNORMAL
end;
if ShellExecuteEx(#exInfo) then
begin
while GetExitCodeProcess(exInfo.hProcess, exitcode)
and (exitcode = STILL_ACTIVE) do
Application.ProcessMessages();
CloseHandle(exInfo.hProcess);
end
else
ShowMessage(SysErrorMessage(GetLastError));
I've also tried putting the cmd.exe syntax in a bat file and launching that from shellexecute and it DOES generate the file but there is no content. Running the same bat file from explorer generates the file as expected.
How can I launch Openfiles.exe successfully from ShellExecute?

Answer 1

Your problem is the redirect, >, which only makes sense if you have a command interpreter. And in your code you do not. You have two options:
Call ShellExecuteEx passing a command interpreter to do the work.
Use CreateProcess to execute the other process, but pass a handle to a file as the stdout handle for the new process.
For the command interpreter option you would have a command line like this:
cmd /c Openfiles.exe /query /s 127.0.0.1 /nh >c:\OpenFilesExport.txt
The code might be like so:
FillChar(exInfo, Sizeof(exInfo), 0);
with exInfo do
begin
cbSize := Sizeof(exInfo);
fMask := SEE_MASK_NOCLOSEPROCESS or SEE_MASK_FLAG_DDEWAIT;
lpFile := 'cmd.exe';
lpParameters := '/c Openfiles.exe /query /s 127.0.0.1 /nh >c:\OpenFilesExport.txt';
nShow := SW_SHOWNORMAL;
end;
For the CreateProcess option you'll need to create the file with a call to CreateFile, and pass that handle as stdout of the new process. You'll need to make sure that the file handle is inheritable. And finally you'll need to wait on the process so that you can close the file handle.
Regarding your current code, your wait is not very pleasant. It's a busy wait that needlessly consumes CPU. You should use a blocking wait on the process handle.