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make sure `$area` is otherwise unset to start with. Use + instead of :+ to be able to specify an empty list of areas.
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Stéphane Chazelas
Stéphane Chazelas
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For your specific use case, there's a much easier answer:

unset -v area
if __SOME_SETTING__; then
  area="ca,us"
fi

process_data -i /some/path ${area:+area+ --area "$area" }

If for some reason you can't use arrays, and you need more control than the above practice offers, you might consider using a function wrapper.

withOptionalArea() {
  if __SOME_SETTING__; then
    "$@" --area us,ca
  else
    "$@"
  fi
}

withOptionalArea process_data -i /some/path

...but this should only be necessary in exceptional circumstances.

Really, use an array.

For your specific use case, there's a much easier answer:

if __SOME_SETTING__; then
  area="ca,us"
fi

process_data -i /some/path ${area:+ --area "$area" }

If for some reason you can't use arrays, and you need more control than the above practice offers, you might consider using a function wrapper.

withOptionalArea() {
  if __SOME_SETTING__; then
    "$@" --area us,ca
  else
    "$@"
  fi
}

withOptionalArea process_data -i /some/path

...but this should only be necessary in exceptional circumstances.

Really, use an array.

For your specific use case, there's a much easier answer:

unset -v area
if __SOME_SETTING__; then
  area="ca,us"
fi

process_data -i /some/path ${area+ --area "$area" }

If for some reason you can't use arrays, and you need more control than the above practice offers, you might consider using a function wrapper.

withOptionalArea() {
  if __SOME_SETTING__; then
    "$@" --area us,ca
  else
    "$@"
  fi
}

withOptionalArea process_data -i /some/path

...but this should only be necessary in exceptional circumstances.

Really, use an array.

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Charles Duffy
Charles Duffy
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  • 22

For your specific use case, there's a much easier answer:

if __SOME_SETTING__; then
  area="ca,us"
fi

process_data -i /some/path ${area:+ --area "$area" }

If for some reason you can't use arrays, and you need more control than the above practice offers, you might consider using a function wrapper.

withOptionalArea() {
  if __SOME_SETTING__; then
    "$@" --area us,ca
  else
    "$@"
  fi
}

withOptionalArea process_data -i /some/path

...but this should only be necessary in exceptional circumstances.

Really, use an array.