Re: trap DEBUG and $_

[isabella parakiss]

On 10/11/15, Dan Stromberg <dstromberglists@gmail.com> wrote:
> Is there a way of outputting a datestamp to shell stderr at the _beginning_
> of the execution of a command, that won't wipe out $_?
>
> I use $_ quite a bit for the last argument to the previous command,
> interactively.  And I'd like to datestamp all my commands. Datestamping
> after with $PS1 is easy, but datestamping before is a little harder.
>
> I've tried using:
>
>    function preexec { if tty -s; then echo "$(tput smso)cmd started $(date
> +%Y\ %a\ %b\ %d\ %r)$(tput rmso)"; fi; }
>    trap preexec DEBUG
>
> ...but as you might suspect, I'm finding that $_ is always "preexec" with
> this enabled.
>
> Any suggestions?
>
> Thanks!
>
trap '__=$_; preexec; : "$__"' DEBUG

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xoxo iza