* special char display
** we only expect ascii values
** 1) <undef> == 0, 2) control+key, 3) ^?, 4) regular chars
** no need for a table, just use conditions and arithmetic
** ^? can just be a special case, or can be handled bitwise
    (c_cc[index]-1+'A') & 0x7F
** special case for <undef> can use either '\0' or _POSIX_VDISABLE

* error reporting
** always exit non-zero in error conditions
** perror and strerror are only for cases where errno is set
** either is fine

    fprintf(stderr, "%s: unable to do a thing to %s: %s\n", 
            prog, arg, strerror(errno));

    fprintf(stderr, "%s: unable to do a thing to ", prog);
    perror(arg);

** all other cases (no errno value) just use fprintf(stder, "...", ...);
** you only have to support single char input for control chars
    is there an arg?
    does strlen say 1?
    no processing is needed, just stuff it in the array as is

    reminder: lnext == terminal escape
              e.g., to reliably input the backspace, Ctrl+V <backspace>
                    results in the one char value ^?

** test script in the case of bad arguments is OK with just "invalid argument"
    "invalid .*argument"
** expects a single error report

* min and time
** how are they different?
*** only accept numeric values
*** must be in the range 0-255 because it's still a char value
*** displayed as a number, not a char
*** argument must be convertable to a number, and the result is in the
    acceptable range (above)


* demotwo part of the assignment

    The posix standard has a good page with descriptions of canonical and 
    non-canonical mode, and what min and time do.
    https://pubs.opengroup.org/onlinepubs/009696799/basedefs/xbd_chap11.html#tag_11
    Read that first.

** not a huge part of the assignment, don't sink too much time into it.
   we just want to see that you understanding what the terminal settings are
   for.

* stty -a
** line represents the "line discipline", basically the glue between the
   device and the device driver
** see ioctl_tty for details about getting and setting the value
** your program does not need to handle this, just here for information