The fork() system call will spawn a new child process which is an identical process to the parent except that has a new system process ID. The process is copied in memory from the parent and a new process structure is assigned by the kernel. The return value of the function is which discriminates the two threads of execution. A zero is returned by the fork function in the child's process.
This tutorial will cover the creation of child processes and process control using fork, exec and other C library function calls using the GNU "C" compiler on the Linux operating system.