"4. Add Directories To the Directory Stack With PUSHD
"While we're on the subject of directories, let's talk about the
directory stack. Quite simply, this is a list of directories stored
by bash. The currently-browsed directory always tops the list, but
the list is otherwise empty until you add a new directory, which
you can do using the pushd command. For example, pushd /usr/bin
will add /usr/bin. It will also switch you to that directory, so
you could use it instead of cd to navigate (the -n command option
will let you add a directory but stay where you are). The dirs
command will show the directory list (remember that the
currently-browsed directory will always be at the top). popd
deletes the topmost entry in the list, and switches you to the next
in the list. Give the directory list a try. It can be very useful
if you're administering a system and have to leap from directory to
directory, and are inclined to forget where important things
are."
