seach and replace globally
:%s/old_text/new_text/g
search and replace interactively
:%s/old_text/new_text/c
search and replace a text in current line
:.s/old_text/new_text
There are two types of researchers. Those who have done something and those who haven't. The latter will say there are 143 ways to do something, and the former will say 142 of them don't work. - Quote from a System V researcher