Re: [tlug] Linux Quiz: Call For Questions

[Jens Oliver John <lists@example.com>]

On Sun, Apr 27, 2014 at 06:00:09PM +0200, Bruno Raoult wrote:
> On Sun, Apr 27, 2014 at 5:15 PM, Daniel A. Ramaley <daniel.ramaley@example.com
> > wrote:
> 
> > On 2014-04-28 at 00:06:13 Stephen J. Turnbull wrote:
> > > Or how about a password with a literal backspace in it?
> >
> > I'm having trouble figuring out how a password input method would know
> > whether you meant to backspace, or to insert a backspace character. I
> > like it! How about a password with a literal carriage return?
> >
> > It seems in my terminal i can type literal backspace and carriage
> > returns by preceding them with ctrl-q. For me to want to use one in a
> > password, i'd have to be confident that all password input methods would
> > accept workarounds like that though.
> >
> 
> I am not sure to understand... Of course a ctrl-q can help for some
> characters.
> For some only.
> Tell me how to input the the zero character? Would this one be forbidden?
> And 2?
> and 3? and many others, beside backspace?

Technically, according to POSIX.1-2008[0], every character/byte sequence is
permitted in filenames except for the slash '/' and NULL character '\0'. 

Input is possible if the terminal or editor etc allows for it. In vim for
example, to input NULL type ^V10 (NULL byte ahead: ) in insert mode. In the
Urxvt terminal emulator, you can write to the terminal by inputting the
character code in hexadecimal, so every character could be entered, including at
password prompts.

--
[0]:  http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html,
      Section 3.170.