rk9005@cca.ucsf.edu (Roland McGrath) (04/23/88)
Index: 4.3 BSD and Sun 3.2 (and greater, probably), csh
I have repeated this on 4.3 BSD Vaxen and Sun Unix 3.2 Sun 3/50s.
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.
I guess most people don't set history to a big number, so they haven't
noticed it. This will also happen using `!!:s/foo/bar' or '!2:s/foo/bar',
as well as with the trailing ^ or / appended.
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?chris@mimsy.UUCP (Chris Torek) (04/23/88)
In article <1245@ucsfcca.ucsf.edu> rk9005@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@mimsy.umd.edu Path: uunet!mimsy!chrisrk9005@cca.ucsf.edu (Roland McGrath) (04/24/88)
["csh history bug"] - chris@mimsy.UUCP (Chris Torek): ) 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. Sorry, I don't have source access. This should, of course, be fixed to set the event number to INT_MIN so that even with history=INT_MAX, it will work correctly. ) -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!). Ack! I should have expected should stupidity from Unix! Oh well. Maybe I'll fix it when Berkeley declares csh free. ) In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) ) Domain: chris@mimsy.umd.edu Path: uunet!mimsy!chris
strike@convex.UUCP (Professor Fate) (04/26/88)
I have fixed this bug. Csh uses the value "-1000" to mark internal, temporary history events created during substitutions. When history is very large as in "set history=2000", the set of events to keep is much larger and subsequent history processing will include the temporary events. These temporary events are usually thrown away after each command because csh asks: if (history counter - event number) > history value, then toss this event. If history value ~ 2000, and event number = -1000 ( ==> temporary), you can see why the shell would choose to keep the temp event. To apply the fix, change the last return statement in function dosub() in file sh.lex.c to return -32767 instead of -1000. This will allow history to be set to ~32767 (Big!) without errors. M -- Finally then, I will read you your rights... You have the right to remain silent. You are warned that anything you say can and will be taken down and used as evidence against you. Listen to this. Run. -The Clash "Know Your Rights"