It’s how all new processes in Unix are created. There is no “spawn new process running this code” operation. Instead:
(1) you duplicate yourself with fork()
(2) the parent process continues about its business
(3) the created process calls execve() to become something else
This is the mechanism by which all new processes are created, from init (process 1) to anything you run from your shell.
Real life examples here, in this example of a Unix shell:
https://github.com/mirror/busybox/blob/master/shell/ash.c
