How to disable command prompt history?

[Kevin Hunter]

At 1:56p -0400 on 02 Jun 2007, sac wrote:
> On 6/2/07, Christopher Hilton <chris at vindaloo.com> wrote:
>> VeeJay wrote:
>>> Could someone would like to describe that how we can disable to show 
>>> last executed commands by pressing Up Arrow?
>>>
>> 
>> That would depend on which shell you are running. Can you run the 
>> following command and post the results here?
>> 
>>      echo $SHELL
> 
> By default most of the shells like bash, zsh, ksh have history option. 
> But you can avoid writing the history of the current session to the 
> history file by unsetting the HISTFILE environment variable.
> So next time when you login the history of the previous session will
> not be shown.

I'd be curious as to the underlying "why?".  Having a history of what
you've done is generally a Good Thing.  The only reason that I
personally have ever come across to necessitate not storing my actions
is when I'm playing a prank on one of my friends.  Other than that,
having the ability to go see what commands I was executing three years
ago comes in awful handy.  I /could/ recreate that arcane command
sequence for that one-off job I needed 1,237 days ago, or I could do a

history | grep 'substring I remember in command' | less

And, if you're worried about the space it takes to store the history,
don't.  It's extremely negligible.

Kevin