$ cd build/
$ cd -
-: No such file or directory
$

int do_cd(int argc, const char **argv) {
    const char *path;
    if (argc > 1) {
        path = argv[1];
    }
    else {
        path = getenv("HOME");
        if (path == NULL) {
            fprintf(stderr, "No HOME environment variablen");
            return 1;
        }
    }
    if (chdir(path) < 0) {
        perror(path);
        return 1;
    }
    return 0;
}