On 18/05/2016 13:42, Max Ivanov wrote:
can backtick (or combination of other scripts commands) can be to NOT
set env var on error?
Not if it succeeds.
However, backtick -i will exit on error: you can use that difference in
program flow to create the sequence you need.
backtick -n MAYBE_ARG { /bin/false }
import -u MAYBE_ARG
s6-echo ${MAYBE_ARG} $@
Note that it's intentional that you always get an argument when
expanding ${MAYBE_ARG}. That's a feature of execline. If you want an
empty ${MAYBE_ARG} to expand to zero word, you need to split the
substitution.
I could add `-s` flag, to `import` and it solves problem for an empty value,
but it also splits non empty value which is not desirable.
Use a splitting delimiter that cannot appear in your value.
--
Laurent
