Originally Posted by pixellany
One really neat trick is "man -k keyword". E.g: to find commands relating to files: "man -k file"
$ apropos whatever
is the same thing. But easier to remember IMHO.
What it does is search the titles of man pages for the word 'whatever'.
I use it all the time. (Not stricktly on topic, perhaps, but ctrl-r does a reverse history search and is also unbelievably useful, for example ctrl+r up might yeild 'updatedb', hitting ctrl-r again another comand with up in it....)