Best Unix Tricks?
jrockway: My tip: pushd without an arg pushes the current directory onto the stack, and then switches to what popd would have.  Hence, repeated invocations of pushd let you cycle between two directories without thinking.$CDPATH is also amusing:  $ mkdir /foo/bar/baz
  $ cd baz
  bash: cd: baz: no such file or directory
  $ export CDPATH="/foo/bar"
  $ cd baz
  $ pwd
  /foo/bar/baz