Bug 3275

Summary: how to set meta-delete key binding
Product: [Retired] Red Hat Linux Reporter: Joe Harrington <jhmail>
Component: tcshAssignee: Eido Inoue <havill>
Status: CLOSED DEFERRED QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: 5.2   
Target Milestone: ---   
Target Release: ---   
Hardware: i386   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
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Clone Of: Environment:
Last Closed: 1999-09-02 18:08:08 UTC Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Embargoed:

Description Joe Harrington 1999-06-04 20:21:08 UTC 
I've been trying to set the key binding for meta-delete.
I'm running in an xterm and have used xmodmap to cause both
backspace and delete to issue delete (0xff) in vt100-type
windows.  This fixes a lot of things and the only thing that
this breaks is meta-backspace in tcsh.  So I need to set
meta-delete in tcsh but tcsh appears not to allow it to be
set.

The tcsh man page states that delete is given as ^? and that
you can say bindkey -b 'M-<keyname>' <command> to set meta
keys.
However:
% bindkey -b 'M-^?' backward-delete-word
Bad key spec M-^?

If I use ^V to quote the meta-delete sequence, I get ^H,
which is backspace (0x08), not delete (0xff).  Using ^H in
any bindkey command affects backspace but not delete.
Doing just bindkey to list the sequences lists a bunch of
meta sequences like "^^g".  Perhaps one of these is what I
want but I have no way of knowing which of those sequences
corresponds to meta-delete, nor do I know how to generate
them.  Cutting and pasting them works to some windows, but
not to shell windows.

The man page tells you how to set delete and anything with a
meta in front of it, but combining those rules does not
work.  Please fix, or suggest (and document in the man page)
another way.

Thanks!
Comment 1 Jeff Johnson 1999-06-05 16:11:59 UTC 
Have you tried entering the command all in ascii? By that I mean
instead of trying to get the code \0xff into the command, try
the key sequence
	M
	-
	^	caret
	?	question mark

when entering your bindkey command?


------- Email Received From  Joe Harrington <jh.cornell.edu> 06/07/99 11:57 -------
Comment 2 Joe Harrington 1999-06-07 16:05:59 UTC 
(Here's the contents of the email I sent.  Sorry, I thought it would
appear in the dialog.)

Yes I tried, no it doesn't work.  Trying this suggestion will show
that it produces the following error message:

% bindkey -b 'M-^?' backward-delete-character
Bad key spec M-^?

I tried both the quoted key sequences and the ascii equivalents for
^?, ^H, ^h, ^_, M-DL, M-DEL, M-0xff, and all of the "untypable"
foreign characters that show up when you do bindkey without arguments,
by cut-and-paste from the window.

Apparently bindkey -b limits the sequence to three characters, and
they have to be printable.  The sequence 'M-C-s' fails, for example.
My belief is that there is an anti-loophole in the key codes for
bindkey: You can only tell bindkey to use "meta" in the -b format, and
you can only tell bindkey about delete using ^?.  This latter sequence
is documented but is disallowed by the -b format, so meta-delete isn't
possible.  DEL is the only ascii sequence that is not printable and
that is not in the first ascii register (values 0x00 - 0x1f).

A very easy fix to code would be to extend the -b option to include 1)
the standard ASCII two- and three-letter expansions of the control
characters (NUL, SOH, STX, etc.), 2) Multiple "shift"-style prefixes
(M-C-x), and/or 3) hex values in the "0x" format (M-0xff).
Comment 3 Jeff Johnson 1999-09-02 18:08:59 UTC 
This won't be in Red Hat 6.1. I'm preserving the bug by changing the
state to REMIND.