Er, yes. But it is through the agency of the execve(3) system call that this happens - you can see the code for this (for example) in /arch/i386/kernel/process.c in the Linux source. Okay in Linux it is further complicated by the binfmt_misc stuff, but in general for all Unix based OS execve is a kernel function that is exposed via the syscall mechanism in the C standard library.

/J\