How can I get unique values from an array in Bash?

Question

I\'ve got almost the same question as here.

I have an array which contains aa ab aa ac aa ad, etc. Now I want to select all unique elements from this ar

Answer 1

this one will also preserve order:

echo ${ARRAY[@]} | tr [:space:] '\n' | awk '!a[$0]++'

and to modify the original array with the unique values:

ARRAY=($(echo ${ARRAY[@]} | tr [:space:] '\n' | awk '!a[$0]++'))