I think I understand the instructions given in [How to add a directory to the PATH?](https://askubuntu.com/questions/60218/how-to-add-a-directory-to-my-path) about adding directories to $PATH. But I don't understand how to add directories to $MANPATH or $INFOPATH.

Also -- in googling around for help I have noticed that sometimes directions say `export PATH=/usr/share/lib/something:$PATH` and sometimes they say `export PATH=$PATH:/usr/share/lib/something`. Which is it?