Re: [Bug-readline] Confused about the behaviour of bind-tty-special-chars

[Richard Michael]

On Sat, Sep 3, 2011 at 8:59 PM, Chet Ramey <address@hidden> wrote:
> On 9/3/11 11:15 AM, Richard Michael wrote:
>> Hello everyone,
>>
>> MacOS 10.6, macports provided bash 4.2.10(2) compiled against macports
>> readline-6.20.
>>
>>
>> I've turned off special char binding:
>>
>> $ cat ~/.inputrc
>> set bind-tty-special-chars off
>>
>> $  bind -v | grep special-chars
>> set bind-tty-special-chars off
>>
>>
>> However, readline still binds functions for \C-u, \C-w and other tty
>> keyseqs (such as HOME, END).
>>
>> $ bind -p | grep '\C-[uw]'
>> "\C-u": unix-line-discard
>> "\C-w": unix-word-rubout
>>
>> $ bind -q beginning-of-line
>> beginning-of-line can be invoked via "\eOH", "\e[H".
>>
>>
>> Why?  After turning off the special char binding, I expected to see
>> these keyseqs as self-inserting and the functions as unbound.
>
> Those are the default readline key bindings.  The defaults exist
> regardless of whether or not readline takes the extra step to make
> sure the tty special chars are bound to their readline equivalents.
> The bind-tty-special-chars variable caters mostly to those who bind
> their tty special characters to values other than the defaults.

Thank you very much for quick reply and clear explanation.  Is there a
list of these defaults (or, which source file contains them)?  I offer
to contribute them to the manual.  (Did I miss it?)


> However, readline binds functions to the arrow and keypad keys on each
> invocation.  There's not currently any way to turn that off.
> `bind -u beginning-of-line' will remove the default binding to ^A, but
> leave the arrow key bindings intact.

Yes, sorry, I could have mentioned that I did notice "bind -u .. "
would remove a binding I configured myself, but that it always
retained the PGUP, HOME, etc. bindings.  How it was determining the
PGUP, HOME, etc. keyseqs was the next thing I was going to
investigate.


Regarding default bindings, the manual indicates many "defaults", ex.
\C-a beginning-of-line.  These do not work out-of-the-box on my
readline, I've had to add them to an inputrc.  How should I understand
"default" in the documentation: "configured by the inputrc which ships
with the readline library and may therefore be broken by a vendor on
your system", or, "hard coded in readline" (such as above, \C-u
unix-line-discard and \e[H beginning-of-line, etc.)?


Regards,
Richard