Question

I’m trying to modify a legacy Delphi 5 app so that it can be launched either from it’s icon/via Explorer, or from the console (command-line). When it gets launched from the console, I want the program to detach itself from the console process, so that the console can continue to execute other instructions without waiting for my program to terminate.

I want to use it in a ‘batch’ file, such that I might have;

 @echo off rem step 1 - do some stuff here rem rem step 2 - launch my app c:\myfolder\myapp rem rem step 3 - do some more stuff here 

and that the console process moves on to step 3 straight after launching my app in step 2.

I’m sure I’ve done this before, many years ago, but I’m puzzled as to what exactly I did. I don’t want to write a tiny console app ‘launcher’ for my main Windows app – I’m 95% sure that there was a way of doing this within a ‘normal’ Delphi GUI app.

I guess I could use vbscript or powershell or something to ‘execute’ my program with some kind of ‘nowait’ parameter but the client is familiar with batch files and I don’t really want to upset the applecart by suggesting he change his scripts or install additional stuff – I’m making changes to the executable anyway and it would be great to tick this box for him too.

Anyone? 🙂

Answer 1

I think the START command is the one you’re looking for. It starts a process separately to the console and it’s part of cmd.exe so no extra software required.

But I was of the opinion that GUI apps did this anyway. Maybe Delphi is different to MSVC.

Open up a console and type 'start /?'.

As itowlson states in the comments, GUI application do generally detach themselves. It’s the actual cmd.exe shell doing trickery in that it waits for it to finish if it’s running from a cmd file.

So 'notepad' from the prompt will start it in the background but 'notepad' within a cmd file will wait. Within the cmd file, you need to use:

start notepad.exe 

or whatever your application is called (not notepad, presumably).