How to use feof and ferror for fgets (minishell in C) [duplicate]

Answer 1

fgets(str, LINE_LEN, stdin);

if (str==NULL) {
    goto errorfgets;
}

That's not how you check the return value of fgets. What's more, in your code str will never be NULL by definition. You want something like:

if (!fgets(....)) }
    /* error handling. */
}