Makeing history harmless

Makeing history harmless

[Meino Christian Cramer]

Hi,

 there are several kind of commands -- mainly things like "rm" --
 which may be harmless only in a certain context.

 The history function of zsh remembers the command but not the
 contents.

 Therefore one may look up (for example via ^R) the history and gives
 a "go" to a command, which he _really_ does not want by accident.

 Is it possible to write a "something" to filter out certain commands 
 or to modify certain commands before they were copied from the
 commandline into the history ?

 Kind regards and keep hacking!
 mcc

Re: Makeing history harmless

[Phil Pennock]

On 2006-10-12 at 04:47 +0200, Meino Christian Cramer wrote:
>  Is it possible to write a "something" to filter out certain commands 
>  or to modify certain commands before they were copied from the
>  commandline into the history ?

(1) setopt hist_ignore_space
    Then get used to typing a space at the start of the line of
    dangerous commands.  The item remains in the history only until the
    next command is run.

(2) Combine that option with a new accept-line to apply it automatically

-----------------------------< cut here >-------------------------------
setopt hist_ignore_space

function histfilter-accept-line {
  emulate -L zsh
  case ${${(z)BUFFER}[1]} in
  (rm|rmdir) BUFFER=" $BUFFER" ;;
  esac
  zle .accept-line
}

zle -N histfilter-accept-line
zle -A histfilter-accept-line accept-line
-----------------------------< cut here >-------------------------------

Regards,
-Phil

Re: Makeing history harmless

[Chris Johnson]

Phil Pennock sent me the following 0.9K:

> On 2006-10-12 at 04:47 +0200, Meino Christian Cramer wrote:
> >  Is it possible to write a "something" to filter out certain commands 
> >  or to modify certain commands before they were copied from the
> >  commandline into the history ?
> 
> (1) setopt hist_ignore_space
>     Then get used to typing a space at the start of the line of
>     dangerous commands.  The item remains in the history only until the
>     next command is run.

It took me a bit to catch on to the fact that the most recently executed
line is always in the history.

> (2) Combine that option with a new accept-line to apply it automatically
> 
> -----------------------------< cut here >-------------------------------
> setopt hist_ignore_space
> 
> function histfilter-accept-line {
>   emulate -L zsh
>   case ${${(z)BUFFER}[1]} in
>   (rm|rmdir) BUFFER=" $BUFFER" ;;
>   esac
>   zle .accept-line
> }
> 
> zle -N histfilter-accept-line
> zle -A histfilter-accept-line accept-line
> -----------------------------< cut here >-------------------------------

I do this with:

   setopt hist_ignore_space
   alias rm=' rm'

Is there an advantage to using the widget?

-- 
Chris Johnson
cjohnson@cs.utk.edu
http://www.cs.utk.edu/~cjohnson

Re: Makeing history harmless

[Phil Pennock]

On 2006-10-12 at 09:15 -0400, Chris Johnson wrote:
> Phil Pennock sent me the following 0.9K:
> > On 2006-10-12 at 04:47 +0200, Meino Christian Cramer wrote:
> > >  Is it possible to write a "something" to filter out certain commands 
> > >  or to modify certain commands before they were copied from the
> > >  commandline into the history ?

> I do this with:

I do neither, I was just helping the OP, Meino.  :^)

>    setopt hist_ignore_space
>    alias rm=' rm'
> 
> Is there an advantage to using the widget?

Not really, unless you want to avoid global aliases whilst writing
something which can special-case things like "svn rm"; you could have
nested case statements examining different items in ${(z)BUFFER} and
possibly triggering other effects too.  Heck, build a whole new dispatch
system for command hooks, a la compsys.  ;^)

In summary, zsh is mighty and there's more than one way to do it.

-Phil