BASH - Prompt - Trim Long Directory Paths

cd /usr/lib/systemd/user/sockets.target.wants

shows the prompt as:

bigmamba:/usr/lib/systemd/user/sockets.target.wants$

Configure bash to display only the last two directories of the path

export PROMPT_DIRTRIM=2

now shows the prompt as:

bigmamba:.../user/sockets.target.wants$