Every possible combination of given letters in BASH

If you want to create every possible word or combination of letters (or any other characters) you can use very simple BASH function:

$ echo {a..c}

This command will print all possible letters starting with a and ending on c (inclusive), so the result is:

a b c

You can get every possible combination of letters from the given range, which length is larger than 1, i.e.:

$ echo {a..c}{a..c}

This command will print every possible combination of letters starting with a and ending on c (inclusive) with another letter from the same range. The result is:

aa ab ac ba bb bc ca cb cc