bash prompt help

Hi all,

Running Bash 4.2.20, I would like to have a prompt composed by the first 
letters of the base path, excluding the last one.


Example:
- /u/l/bin if I'm in /usr/local/bin
- /v/w/h/my-website if I'm in /var/www/html/my-website
- /h/mihamina if I'm in /home/mihamina

Of course, this could lead to some errors and confusion, but it's useful 
for my particular use case, and if I want to explicitely print the 
current directory, I'll just have to "cwd".

Thank you.

-- 
RMA.