in error messages, do not output raw non-printable characters to the terminal

[Vincent Lefevre]

In error messages, raw non-printable characters from arguments should
not be output without transformation, at least if this is on a terminal.
If stderr has been redirected, this is more a matter of choice.

An example: type "cd /^M" where ^M is a CR character (e.g. obtained by
typing ^V ^M). One gets on the terminal:

: No such file or directory

which is not very informative. This leads to this kind of questions:

  
http://unix.stackexchange.com/questions/154408/cant-cd-to-home-user-when-sourcing-a-script

IMHO, in this case, bash should do like zsh, which replaces the CR
character by the character sequence "^M".

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)