Question

The following code returns -1, how can I know what’s wrong?
get a detailed error or something?

if (read(programFile, value, sizeof(FRAME)) == -1) {
        return SYSTEM_CALL;
    }

Answer 1

You need to look into errno, which is a variable set by system calls to indicate an error. You can use the convenience function perror to get a human-readable printout.

if (read(prog, value, sizeo(FRAME) == -1) {
  perror("read");
  // handle error
}

It can return something like No such file or directory. Either way its a good practice to use it.

Check out man errno and man perror for more information.