FOR WINDOWS USERS

i had a look to start command. it's really usefull in fact.

this is how i launch a specific Apache SSL server

<?php
$cmd = "start /D C:\OpenSA\Apache /B Apache.exe -D SSL";
exec($cmd,$output,$rv);
?>

/D specify the path where application will be launched (equivalent to cd to path)
/B launch application without a console window

so to know the exact parameters of start, you could use

<?php
exec("start /? > start.txt");
?>

and you will get the help of start in a file named 'start.txt' in the same place you run the script

for WIN 98 you may need to modify a little your command

exec("COMMAND.COM /C START program args >NUL");

(taken from another post)