Bug#872956: [debian-policy] warn about danger of pipe in shell snippet of makefile

[Jonathan Nieder]

Hi,

Bastien ROUCARIÈS wrote:

> set -e is not suffisant to detect error in pipe context
>
> cat nonexistant | sed s/some//g will hapilly return 0 and do not fail
>
> exec 3>&1; s=$(exec 4>&1 >&3; { cat nonexistant ; echo $? >&4; } | sed 
> s/some//g ) && exit $s
>
> this could be simplified by using make function
> PIPESAFE=exec 3>&1; s=$$(exec 4>&1 >&3; { $(1) ; echo $$? >&4; } | $(2)) && 
> exit $$s
>
> Could deserve a footnote on 4.6. Error trapping in makefiles

I don't think this belongs in policy.  Maybe devref?

By the way, if you're using bash
(https://www.gnu.org/software/make/manual/html_node/Choosing-the-Shell.html),
you can use "set -o pipefail" to handle this kind of case.

Thanks,
Jonathan

Bug#872956: [debian-policy] warn about danger of pipe in shell snippet of makefile

[Bastien ROUCARIÈS]

Package: debian-policy
Version: 4.0.1.0
Severity: normal

set -e is not suffisant to detect error in pipe context

cat nonexistant | sed s/some//g will hapilly return 0 and do not fail

exec 3>&1; s=$(exec 4>&1 >&3; { cat nonexistant ; echo $? >&4; } | sed 
s/some//g ) && exit $s

this could be simplified by using make function
PIPESAFE=exec 3>&1; s=$$(exec 4>&1 >&3; { $(1) ; echo $$? >&4; } | $(2)) && 
exit $$s

Could deserve a footnote on 4.6. Error trapping in makefiles





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