Re: Make ON_ERROR_STOP stop on shell script failure

On Fri, Mar 24, 2023 at 2:16 PM Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
wrote:

>
>
> On Fri, Mar 24, 2023 at 11:07 AM Peter Eisentraut <
> peter(dot)eisentraut(at)enterprisedb(dot)com> wrote:
>
>> On 20.03.23 19:31, Greg Stark wrote:
>> > So I took a look at this patch. The conflict is with 2fe3bdbd691
>> > committed by Peter Eisentraut which added error checks for pipes.
>> > Afaics the behaviour is now for pipe commands returning non-zero to
>> > cause an error*always* regardless of the setting of ON_ERROR_STOP.
>>
>
> Commit b0d8f2d983cb25d1035fae1cd7de214dd67809b4 adds SHELL_ERROR as a set
> to 'true' whenever a \! or backtick command has a nonzero exit code. So
> it'll need some rebasing to remove the duplicated work.
>
> So it's now possible to do this:
>
> \set result = `some command`
> \if :SHELL_ERROR
> -- maybe test SHELL_EXIT_CODE to see what kind of error
> \echo some command failed
> -- nah, just quit
> \q
> \endif
>
>
>> > I'm not entirely sure that's sensible actually. If you write to a pipe
>> > that ends in grep and it happens to produce no matching rows you may
>> > actually be quite surprised when that causes your script to fail...
>>
>
> I agree that that would be quite surprising, and this feature would be a
> non-starter for them. But if we extended the SHELL_ERROR and
> SHELL_EXIT_CODE patch to handle output pipes (which maybe we should have
> done in the first place), the handling would look like this:
>
> SELECT ... \g grep Frobozz
> \if :SHELL_ERROR
> SELECT :SHELL_EXIT_CODE = 1 AS grep_found_nothing \gset
> \if :grep_found_nothing
> ...not-a-real-error handling...
> \else
> ...regular error handling...
> \endif
> \endif
>
> ...and that would be the solution for people who wanted to do something
> more nuanced than ON_ERROR_STOP.
>
>
Dangit. Replied to Peter's email thinking he had gone off Greg's culling of
the recipients. Re-culled.