I'm late to respond, but here is how I do it:
const char *progname = "./yourProgName";
const char *argument1 = "arg1";
const char *argument2 = "arg2";
if (fork() == 0)
// We are the child process, so replace the process with a new executable.
execl(progname, progname, argument1, argument2, (char *)NULL);
// The parent process continues from here.
First, you fork() the process to create a new process. It still has the same memory space as the old one. fork() returns for both parent and child processes. If fork() returns zero, you are the child process. The child process then uses execl() to replace the process memory with one from a new file.
Notice that progname is given twice to execl(). The first is what execl() will actually try to run, the second is argv. You must provide both or the argument count will be off by one. Progname must contain all the required path information to find the desired executable image.
I give two arguments in this example, but you can pass as many as you want. it must be terminated with NULL, and I think you have to cast it as (char *) like I show.
This approach gives you a fully independent process with arguments and a unique pid. It can continue running long after the parent process terminates, or it may terminate before the parent.