Andrew Janke wrote:
> # go to wherever you were before
> alias b="cd ${OLDPWD}"
In bash and probably other shells, "cd -" is a built-in shorthand for
"cd $OLDPWD".
Also check out "pushd", "popd" and "dirs" which let you manage a stack
of directories (so for example you could alias pushd as cd and then use
popd as a multi-level back button).