${(u)…}: Deduplicate words

u expands only the first occurrence of each word, i.e. it does not show duplicates in the result.

Links

• Zsh manual on parameter expansion flags

Examples

Deduplicate words of a string

1 2 3 4 5 6

value="Genius is one percent inspiration and ninety-nine percent perspiration." IFS=" ." # deduplicate echo ${(u)=value} # deduplicate, upper-case, sort echo ${(uUo)=value}

Output:

1 2	Genius is one percent inspiration and ninety-nine perspiration AND GENIUS INSPIRATION IS NINETY-NINE ONE PERCENT PERSPIRATION