> Copying the data segment and immediately overwriting it was inefficient, so several new flavors of "exec" were developed to get around that. The several diff

> Copying the data segment and immediately overwriting it was inefficient, so several new flavors of "exec" were developed to get around that. The several different flavors of exec are just convenience functions that lead to an execve syscall (execl* makes the vector out of some of its args; exec*p searches the path first, etc). Maybe you're thinking of vfork (a restricted fork), which seems to have gone away about when copy-on-write came in.