Вы можете использовать технику, которую я нашел здесь :
CFWriteStreamRef stdoutStream = NULL;
if (verbose) {
CFURLRef devStdout =
CFURLCreateWithFileSystemPath(NULL, CFSTR("/dev/stderr"),
kCFURLPOSIXPathStyle, false);
stdoutStream = CFWriteStreamCreateWithFile(NULL, devStdout);
if (stdoutStream == NULL)
errexit("cannot create CFWriteStream for /dev/stderr");
if (!CFWriteStreamOpen(stdoutStream))
errexit("cannot open CFWriteStream for /dev/stderr");
}