Let's perform the following steps:

1. Crunch is pre-installed with Kali. We can launch it with crunch:

2. As we see, it is easy to generate a password list with a minimum of two characters and a maximum of two characters, containing only abcdef. We can use the following command:

crunch 2 2 abcdef

3. In the following screenshot, we can see the wordlist has been generated:

4. To save it in a file, we can use the –o switch.