bash remove duplicate string from list [duplicate]

Question

I want to delete duplicate strings from a String. Example:

A="Dog Cat Horse Dog Dog Cat"

The string A should look like this:

A="Dog Cat Horse"

How can I write a Shell script for that?

Answer 1

You could use this,

echo "a a b b c c" | tr ' ' '\n' | sort | uniq | tr '\n' ' ' | sed -e 's/[[:space:]]*$//'

Answer 2

If order is not important, you can use an associative array:

declare -A uniq
for k in $A ; do uniq[$k]=1 ; done
echo ${!uniq[@]}