The explain_dup2_or_die function
is used to call the dup2(2) system
call. On failure an explanation will be
printed to stderr,
obtained from explain_dup2(3),
and then the process terminates
by calling exit(EXIT_FAILURE).
This function is intended to be used in a fashion
similar to the following example:
explain_dup2_or_die(oldfd, newfd);
oldfd
The oldfd, exactly as to be passed to the dup2(2) system call.
newfd
The newfd, exactly as to be passed to the dup2(2) system call.
Returns:
This function only returns on success.
On failure, prints an explanation and exits.