void xunlinkat(int dir_fd, const char *pathname, int flags)
{
    if (unlinkat(dir_fd, pathname, flags))
        perror_msg_and_die("Can't remove file '%s'", pathname);
}
void xunlinkat(int dir_fd, const char *pathname, int flags)
{
    if (unlinkat(dir_fd, pathname, flags))
        perror_msg_and_die("Can't remove file '%s'", pathname);
}