RE: Question WHY is gnu make does not stop on error on rule

[Cook, Malcolm]

> On Thu, 2022-12-08 at 19:59 +0100, aotto wrote:
> > HA HA HA - I fund the bug !!
> >
> > I used "-silent" and not "--silent", the "-silent" is parsed as
> 
> That's funny, but I'm not sure why it works differently in 4.4 since that was
> still the case in 4.3, if you use "-silent".
> 
> > MqC.mq.$(MAKE_LNG): | MqC.mq.$(MAKE_LNG).before
> > MqC.mq.$(MAKE_LNG).after
> 
> This usage is dangerous, because:
> 
>   $ false
>   $ echo $?
>   1
> 
>   $ false | cat
>   $ echo $?
>   0
> 
> See how the pipeline swallowed the failing exit code?  The exit code of a
> pipeline is always the exit code of the last statement in the pipeline (here, 
> the
> "cat" program).
> 
> If you want to require bash you can use something like:
> 
>   SHELL := /bin/bash
>   .SHELLFLAGS = -o pipefail -c
> 
> which will force the exit code of a pipeline to be the exit code of the last
> failing command, not the last command.

I'd add that if you're doing this you'll want to use

 .ONESHELL:

to ensure that multiple lines of a recipe execute one after each other in the 
same process.

> 
> If you don't want to require bash, you'll have to get a LOT fancier than 
> simply
> adding a pipe in a variable, if you want to preserve exit codes.
>