Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!well!bryan
From: bryan@well.sf.ca.us (Bryan Higgins)
Newsgroups: comp.unix.shell
Subject: Re: KornShell history numbers
Message-ID: <25677@well.sf.ca.us>
Date: 26 Jun 91 02:48:18 GMT
References: <25628@well.sf.ca.us>
Distribution: comp
Lines: 50

I wrote:


>Does anyone know how the history numbers are handled from login to login?
>That is, if the current command number is, say, 427, and one logs out and logs
>back in, the new current command number might be something like 203, with all
>the previous commands renumbered accordingly.  I've experimented with this a
>little bit, and can't see any logic in the renumbering.

>Actually, I'd like all the old commands renumbered starting at 1 every time I
>log in.  Is there a way to achieve this?

Some of you wrote and suggested I delete the history file at login, but
notice I said renumber =old= commands starting at 1, not throw away the his-
tory completely.  In other words, if my HISTSIZE is 64, I want to be at com-
mand 65 when I log in.  Turns out the shell keeps more than HISTSIZE com-
amnds in the file (though it doesn't let you get at them), so the history
number is big.  How much it deletes from the file when one logs in (it =is=
trimming it time) seems haphazard.

I've solved this with the following:

#include	<stdio.h>
#include	<ctype.h>

main()
{
	int	n;
	char	line[1024];
	char	*p;

	fwrite("\201\001", 1, 2, stdout);
	while (fgets(line, sizeof(line) - 2, stdin)) {
		for (p = line;  isspace(*p);  ++p) {
			;
		}
		n = strlen(p);
		if (n++ & 1) {
			p[n++] = '\0';
		}
		fwrite(p, 1, n, stdout);
	}
}

If the executable is called 'newhist', then

fc -l -63 -1 | newhist > tmp
mv tmp $HISTFILE

at the start of .profile will do the job.