Infinite history size

Infinite history size

[Chris Down]

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Hello,

I am looking to remove the upper limits on the history size in zsh.

In bash, and some other shells, this can be done by nullfying (note: not
unsetting) HIST{,FILE}SIZE, and then making sure readline's
"history-size" is -1. On zsh, doing the same thing with HISTSIZE and
SAVEHIST results in HISTSIZE becoming 1, and SAVEHIST becoming 0.

Setting an indiscriminately high number is not really appropriate -- I
have years of (uniq'd by last usage) history that I would like to
also import, and even that is fairly substantial:

    $ wc -l .bash_history
    32539 .bash_history

Since I don't have any plans for this size to decrease, using a high
number is probably not a wise idea.

How can I do this in zsh?

Thanks.

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Re: Infinite history size

[ZyX]

14.12.13, 14:52, "Chris Down" <chris@chrisdown.name>":
> 
> Hello,
> 
> I am looking to remove the upper limits on the history size in zsh.
> 
> In bash, and some other shells, this can be done by nullfying (note: not
> unsetting) HIST{,FILE}SIZE, and then making sure readline's
> "history-size" is -1. On zsh, doing the same thing with HISTSIZE and
> SAVEHIST results in HISTSIZE becoming 1, and SAVEHIST becoming 0.

It is not possible for history to occupy more memory then you have thus if you think there is no upper limit then you are false.

> 
> Setting an indiscriminately high number is not really appropriate -- I
> have years of (uniq'd by last usage) history that I would like to
> also import, and even that is fairly substantial:
> 
>     $ wc -l .bash_history
>     32539 .bash_history
> 
> Since I don't have any plans for this size to decrease, using a high
> number is probably not a wise idea.

You should determine how much memory you have, how much of it you can allow to be occupied by the history (AFAIK it is always fully loaded into memory) and act accordingly. Removing the limit is not wiser as it leaves you with an idea that there is no limit while it is always limited by available resources.

Or if you do not think you will ever hit a problem with resource exhaustion you can just set HISTSIZE to LONG_MAX from limits.h: it is the maximum number HISTSIZE can have.

> 
> 
> How can I do this in zsh?
> 
> Thanks.

Re: Infinite history size

[Chris Down]

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On 2013-12-14 15:49:12 +0400, ZyX wrote:
> It is not possible for history to occupy more memory then you have
> thus if you think there is no upper limit then you are false.

While true, any "infinite" related to resource consumption in computer
science has similar restrictions related to the environment, I
considered it an implicit caveat of my request.

> You should determine how much memory you have, how much of it you can
> allow to be occupied by the history (AFAIK it is always fully loaded
> into memory) and act accordingly. Removing the limit is not wiser as
> it leaves you with an idea that there is no limit while it is always
> limited by available resources.
>
> Or if you do not think you will ever hit a problem with resource
> exhaustion you can just set HISTSIZE to LONG_MAX from limits.h: it is
> the maximum number HISTSIZE can have.

So I'll take the answer as "you can't" (although LONG_MAX is obviously
not something that I'm going to reach :-) ).

Thanks anyway.

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Re: Infinite history size

[Bart Schaefer]

On Dec 14,  6:48pm, Chris Down wrote:
} 
} In bash, and some other shells, this can be done by nullfying (note: not
} unsetting) HIST{,FILE}SIZE, and then making sure readline's
} "history-size" is -1.

I think what you've found there is a behavior of readline, not especially
a behavior of the shells in question.  Since zsh doesn't use readline, ...

On Dec 14,  7:53pm, Chris Down wrote:
}
} So I'll take the answer as "you can't" (although LONG_MAX is obviously
} not something that I'm going to reach :-) ).

Although setting a very large number is probably the easiest way, you
could do something along these lines:

    SAVEHIST=$(( $(wc -l $HISFILE) * 2 ))
    HISTSIZE=$SAVEHIST
    zshaddhistory() {
      if (( HISTNO == HISTSIZE ));
      then
        (( HISTSIZE *= 2 )) 
	SAVEHIST=$HISTSIZE
      fi
      return 0
    }

I haven't tested that, and obviously it needs some tweaking for cases
where file size actually becomes a significant fraction of LONG_MAX.

Re: Infinite history size

[Bart Schaefer]

On Dec 15, 12:06pm, Bart Schaefer wrote:
>
>     SAVEHIST=$(( $(wc -l $HISFILE) * 2 ))
> 
> I haven't tested that

And plainly so, given the typo for $HISTFILE.