Re: Accessing the evaluated expression which caused an error

[Zach Riggle <zachriggle@xxxxxxxxx>]

> What exactly might you want captured?

Very frequently I build a create an array that contains a command, e.g.

    declare -a cmd=( echo hello world )

And invoke it like:

    "${cmd[@]}"

When I xtrace, it will print out the values inside the array.

    +wat.sh:2> cmd=( echo hello world )
    +wat.sh:3> echo hello world

With TRAPDEBUG or TRAPERR, all I get is the "${cmd[@]}". None of the
Zsh-supplied arrays (funcfilesource etc.) contain that.  I originally
had some hope that $_ would work, but it appears not to.

Zach Riggle

On Fri, Sep 3, 2021 at 12:14 PM Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:
>
> On Thu, Sep 2, 2021 at 6:43 PM Zach Riggle <zachriggle@xxxxxxxxx> wrote:
> >
> > I'm aware of funcsourcetrace, funcstack, and TRAPDEBUG /
> > ZSH_DEBUG_CMD as well, but none of these contain the actual expression
> > evaluated -- just the input to zsh.
> >
> > I know that zsh has the data internally, since "zsh -x" shows the
> > fully-evaluated expression, so that data must be available somewhere,
> > even if it's not exposed in a shell variable.
>
> Hm.  What xtrace does is dump each individual shell word ... it just
> happens to dump them in the order that puts them together as an
> "expression".  But you'll notice it's not actually an expression, it's
> just e.g. a single simple command.  In fact it's even a bit weird for
> some structured commands (look at the output for a "case" statement
> for example).
>
> It's correct that none of this is captured in any sort of format that
> would be usable by a shell script.  It never exists all at once in
> such a format internally.
>
> What exactly might you want captured?