chris@mimsy.UUCP (Chris Torek) (04/06/89)
Date: Wed, 13 Jan 88 20:36:53 EST
From: Chris Torek <chris@gyre.umd.edu>
To: 4bsd-bugs@ucbvax.Berkeley.EDU
Subject: csh mislexes $var1iables
Index: bin/csh/sh.lex.c 4.3BSD Fix
Reference: 4.3BSD/bin/114
Description:
The C shell's `lexical analyser' (if you can call it that)
thinks that variables are either all digits or all numbers.
As far as it is concerned, $a1bc is the variable $a followed
by the string `1bc'. Everyone is happy: the lexer sees a
properly-formed variable ($a) plus a string, and later, the
variable evaluator looks up $a1bc.
If, however, one writes instead ${a1bc}, the lexer is not
happy. It sees a variable (${a) that is not proper: the
closing brace `}' is missing. It complains about variable
syntax (an ambiguous error, but here the real meaning is not
the intended one!), and the evaluator never gets a chance.
Repeat-by:
% set a1=ok
% echo ${a1}
Variable syntax.
% man csh
(read section on shell variable syntax)
Fix:
It seems to work. The code is all twisty and devious, so
maybe it will break something. I doubt it.
Chris
*** sh.lex.c.old Wed Jan 13 20:22:06 1988
--- sh.lex.c Wed Jan 13 20:22:10 1988
***************
*** 373,377 ****
}
} else if (letter(c))
! while (letter(c = getC(DOEXCL))) {
if (np < &name[sizeof name / 2])
*np++ = c;
--- 373,377 ----
}
} else if (letter(c))
! while (letter(c = getC(DOEXCL)) || digit(c)) {
if (np < &name[sizeof name / 2])
*np++ = c;
--
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain: chris@mimsy.umd.edu Path: uunet!mimsy!chris