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Re: Re: How to (properly) remove the last entry from history with command_not_found_handler

Hello Bart,

On 20.07.2014 20:13, Bart Schaefer wrote:
> On Jul 20, 11:04am, Jochen Keil wrote:
> }
> } function command_not_found_handler()
> } {
> }     sed -i '$d' $HISTFILE
> }     return 127
> } }
> }
> } However, I'm not sure if it's ok to manipulate the history file directly
> } with sed, or if I'm risking corruption.
> This is likely to be a problem if the failing command spans more than
> one line (e.g., a "for" loop with command-not-found in the middle of
> it) or if you are using SHARE_HISTORY where there's a race condition
> among shells reading the history and shells (re)writing it.
> There really isn't any way to "properly" remove an entry once it has been
> written to the history file.  You might try some variation of this:
>   zshaddhistory() {  whence ${${(z)1}[1]} >/dev/null || return 2 }
> There are still problems with that for multi-line commands but the right
> way to achieve your desired behavior is to avoid writing out the commands
> you don't want, not to write them and then delete them again.

It was my first thought too, to avoid adding the command at all.
However, I misunderstood/misinterpreted the explanation of the
zshaddhistory hook in the manual. Anyhow, your version works very well,
thank you!

Nevertheless, I start to see why this is probably a not so good idea (or
at least pretty hard to implement). For example:

  $ echo "test"; echox "test"

This is similar to the multi-line example. One basically needs to split
up the command at semicolons and newlines. Then one needs to decide
which of the subcommands is correct and which one not. Finally one needs
to decide if an altered version of the command should go to the history
file or none at all.

I think the possible gains are not worth the effort. I'll stick to your
solution as it covers most of the cases which I care most about: When
I've accidentally mistyped a command or entered other garbage.

Thank you very much again and best wishes,


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