Re: [PATCH v2 02/10] test/telemetry: fix test calling all commands

[David Marchand <david.marchand@redhat.com>]

On Thu, Jun 26, 2025 at 11:53 AM Marat Khalili <marat.khalili@huawei.com> wrote:
> > @@ -15,7 +15,7 @@ call_all_telemetry() {
> >      telemetry_script=$rootdir/usertools/dpdk-telemetry.py
> >      echo >$tmpoutput
> >      echo "Telemetry commands log:" >>$tmpoutput
> > -    for cmd in $(echo / | $telemetry_script | jq -r '.["/"][]')
> > +    echo / | $telemetry_script | jq -r '.["/"][]' | while read cmd
> >      do
> >          for input in $cmd $cmd,0 $cmd,z
> >          do
> > @@ -25,4 +25,5 @@ call_all_telemetry() {
> >      done
> >  }
> >
> > -(sleep 1 && call_all_telemetry && echo quit) | $@
> > +! set -o | grep -q pipefail || set -o pipefail
> > +(set -e; ! set -o | grep -q pipefail || set -o pipefail; sleep 1 &&
> > call_all_telemetry && echo quit) | $@
>
> I 100% agree with the idea, but sadly I'm not familiar with shell scripting enough to suggest or review this diff. Is `for cmd in` always equivalent to `while read cmd`? Is CI ever executing it in bash for our attempt to set pipefail to be justified? Is it idiomatic? I hope someone else here can help with this.

- From my experiment, the difference between 'for cmd in $(xxx)' and
'xxx | while read cmd' is that an error is not propagated in the
former case.

I suppose it has to do with the for loop, as described in POSIX:
"""
Exit Status

If there is at least one item in the list of items, the exit status of
a for command shall be the exit status of the last compound-list
executed. If there are no items, the exit status shall be zero.
"""

On error of the command, there is no item in the list of the for loop,
so the loop is overall evaluated as a success.


- As far as the CI is concened, the unit tests are run on various
distributions, including Fedora at UNH.
Since the default shell for Fedora is bash, then an error would be caught there.


>
> Perhaps this should just be re-written in Python. It depends on a Python script anyway.

Maybe.
Though if we go that way, we would need some refactoring of the
telemetry client script, defining some python class etc...


-- 
David Marchand