csh history bug

[Chris Torek]

In article <1245 at ucsfcca.ucsf.edu> rk9005 at cca.ucsf.edu (Roland McGrath) writes:
-Repeat-by:
-	$ csh -f
-	% set history=5000
-	% echo foo
-	foo
-	% ^foo^bar
-	echo bar
-	bar
-	% history
-	     1  set history=5000
-	     2  echo foo
-	 -1000  echo bar     3  echo bar
-	     4  history
-	%
-
-    Any large value for `history' will do it.  I have been unable to find
-the exact threshold, but anything larger than 2000 will always work, I think.

Not quite.  Anything more than 1000+next_event+2 suffices.  (I.e.,
if this is the very first command, 1004 is enough.)

The history number `-1000' should give a large hint.  If you look
in /usr/src/bin/csh/sh.lex.c you will find where csh enters substitution
events as number -1000.  The idea is that since

-most people don't set history to a big number,

the negative event will be discarded from the history list since
it occurred over 1000 commands ago.

-Aside: Can anyone with source access tell me what type is used for the
-value of `history', so I can make it 32767 or (2^31) - 1, or whatever?

`int', of course.  The variable itself is a string, but it is converted
to an integer whenever needed (once per command!).
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at mimsy.umd.edu	Path:	uunet!mimsy!chris