Bash empty array expansion with `set -u`

Question

I\'m writing a bash script which has set -u, and I have a problem with empty array expansion: bash appears to treat an empty array as an unset variable during e

Answer 1

this may be another option for those who prefer not to duplicate arr[@] and are okay to have an empty string

echo "foo: '${arr[@]:-}'"

to test:

set -u
arr=()
echo a "${arr[@]:-}" b # note two spaces between a and b
for f in a "${arr[@]:-}" b; do echo $f; done # note blank line between a and b
arr=(1 2)
echo a "${arr[@]:-}" b
for f in a "${arr[@]:-}" b; do echo $f; done