Re: About dash as sh

[Nicolas George <george@nsup.org>]

Greg Wooledge (12024-06-21):
> The original message began with the assertion that the OP had run
> across a bug in dash, and gave two URLs, with no description of the bug
> or the impact it was having on their life.
> 
> I read one of the URLs, and the bug is rather obscure.  It involves a
> second script embedded inside a here document inside the first script,
> with the second script being passed to an interpreter process on stdin.
> I'm not surprised that nobody knew about the bug for many years.

The purported bug boils down to this: if you pipe to a non-interactive
shell a command and data for that command, then the non-interactive
shell might read more than just the command as part of its input
buffering and leave less or nothing as data to the command itself.

It is indeed a bug, since the standard says:

  When the shell is using standard input and it invokes a command that
  also uses standard input, the shell shall ensure that the standard
  input file pointer points directly after the command it has read when
  the command begins execution.

But I consider this clause is misguided, it should apply only when the
input is a tty. Relying on it is a terrible idea.

Regards,

-- 
  Nicolas George