sed

I apologize if this has been already answered but i need a simple answer for that one because it is very simple and it will help understand

I have a file called " users "
In this file there is a list of users.
I just want to replace all the users that start with the letter b to be replaced by the letter Z

Please help

Thanks.:rolleyes:

since I don't want to make the mistake of just
giving you the answer, check out:
http://wwwinfo.cern.ch/dis/texi2html/gnu/sed-3.02/sed_toc.html
Your answer can be found here.

Thanks, I was just trying to avoid the reading