Think it through. Yes, both you and xe haven't grasped this. M. Siebennmann's scenario is that argc is 0, and argv[0] is NULL. There's nothing in the quoted

Think it through. Yes, both you and xe haven't grasped this. M. Siebennmann's scenario is that argc is 0, and argv[0] is NULL. There's nothing in the quoted > argv[argc] shall be a null pointer. constraint that that violates. argv[argc] is a null pointer. You have not found a violation of that constraint. The constraint that is violated is, rather, in the Single Unix Specification. It's the SUS that puts the constraint upon how execve() may be invoked by a strictly conformant application, and requires that (as it says twice) argc be "one or greater", because it constrains the first element of the argument vector to be a pointer to a string, not a null pointer. The _only_ leeway is the wiggle room in "associated with", which it devotes an entire paragraph to explaining. More than one standard applies. The idea that only the C standard covers the writing of these programs is wholly wrongheaded. After all, the C standard also allows non-POSIX implementations.