xref: /freebsd-11-stable/contrib/tcsh/eight-bit.me

How to use 8 bit characters
by 
Johan Widen 
(jw@sics.se) 
and 
Per Hedeland 
(per@erix.ericsson.se)

.pp
(Disclaimer: This is really a sketch of an approach rather
than a "how-to" document.
Also, it is mostly relevant to Swedish X Window users...)

.pp
The way I use this facility at present is to add lines such as the following
to my .cshrc:

.nf 
setenv NOREBIND
setenv LC_CTYPE iso_8859_1
foreach key ( \\\\304 \\\\305 \\\\326 \\\\344 \\\\345 \\\\366 )
   bindkey $key self-insert-command
end
.fi

.pp
Note that if I used a system with a reasonably complete NLS
(and a tcsh compiled to use it),
all of the above could be replaced with simply setting the LANG environment
variable to an appropriate value - the NLS would then indicate exactly which
characters should be considered printable, and tcsh would do the rebinding
of these automatically. The above works for tcsh's simulated NLS and for
the NLS in SunOS 4.1 - without the NOREBIND setting, all of the
Meta-<non-control-character> bindings would be undone in these cases.

.pp
These keybindings are the codes for my national characters, but the bindings
(M-d, M-e etc) are not conveniently placed.
They are however consistent with what other programs will see.

.pp
Now: I actually want the character \\304 to be inserted when I press say '{'
together with a modifier key. I want the behavior to be the same not only
in tcsh but in say cat, an editor and all other programs. I fix this by
performing a keyboard remapping with the
.i xmodmap
program (I use X Windows).

.pp
I give xmodmap an input something like the following:

.nf
keycode 26 = Mode_switch
add mod2 = Mode_switch
! if you want Mode_switch to toggle, at the expense of losing
! Caps- or whatever Lock you currently have, add the two lines below
! clear Lock
! add Lock = Mode_switch
! 	Binds swedish characters on ][\\
!
keycode 71 = bracketleft braceleft adiaeresis Adiaeresis
keycode 72 = bracketright braceright aring Aring
keycode 95 = backslash bar odiaeresis Odiaeresis
.fi

or:

.nf
keysym Alt_R = Mode_switch
add mod2 = Mode_switch
keysym bracketleft = bracketleft braceleft Adiaeresis adiaeresis
keysym bracketright = bracketright braceright Aring aring
keysym backslash = backslash bar Odiaeresis odiaeresis
.fi

Another, more portable way of doing the same thing is:

.nf
#!/bin/sh
# Make Alt-] etc produce the "appropriate" Swedish iso8859/1 keysym values
# Should handle fairly strange initial mappings

xmodmap -pk | sed -e 's/[()]//g' | \\
awk 'BEGIN {
	alt["bracketright"] = "Aring"; alt["braceright"] = "aring";
	alt["bracketleft"] = "Adiaeresis"; alt["braceleft"] = "adiaeresis";
	alt["backslash"] = "Odiaeresis"; alt["bar"] = "odiaeresis";
}
NF >= 5 && (alt[$3] != "" || alt[$5] != "") {
	printf "keycode %s = %s %s ", $1, $3, $5;
	if (alt[$3] != "") printf "%s ", alt[$3];
	else printf "%s ", $3;
	printf "%s\\n", alt[$5];
	next;
}
alt[$3] != "" {
	printf "keycode %s = %s %s %s\\n", $1, $3, $3, alt[$3];
}
NF >= 5 && ($3 ~ /^Alt_[LR]$/ || $5 ~ /^Alt_[LR]$/) {
	printf "keycode %s = %s %s Mode_switch\\n", $1, $3, $5;
	if ($3 ~ /^Alt_[LR]$/) altkeys = altkeys " " $3;
	else altkeys = altkeys " " $5;
	next;
}
$3 ~ /^Alt_[LR]$/ {
	printf "keycode %s = %s %s Mode_switch\\n", $1, $3, $3;
	altkeys = altkeys " " $3;
}
END {
	if (altkeys != "") printf "clear mod2\\nadd mod2 =%s\\n", altkeys;
}' | xmodmap -
.fi

.pp
Finally, with the binding of the codes of my national characters to
self-insert-command, I lost the ability to use the Meta key to call the
functions previously bound to M-d, M-e, and M-v (<esc>d etc still works).
However, with the assumption that
most of my input to tcsh will be through the
.i xterm
terminal emulator, I can get that ability back via xterm bindings!
Since M-d is the only one of the "lost" key combinations that was
actually bound to a function in my case,
and it had the same binding as M-D, I can use the following in
my .Xdefaults file:

.nf
XTerm*VT100.Translations:	#override \\n\\
			Meta ~Ctrl<Key>d:	string(0x1b) string(d)
.fi

- or, if I really want a complete mapping:

.nf
XTerm*VT100.Translations:	#override \\n\\
			:Meta ~Ctrl<Key>d:	string(0x1b) string(d) \\n\\
			:Meta ~Ctrl<Key>D:	string(0x1b) string(D) \\n\\
			:Meta ~Ctrl<Key>e:	string(0x1b) string(e) \\n\\
			:Meta ~Ctrl<Key>E:	string(0x1b) string(E) \\n\\
			:Meta ~Ctrl<Key>v:	string(0x1b) string(v) \\n\\
			:Meta ~Ctrl<Key>V:	string(0x1b) string(V)
.fi