CDPATH doesn't require the export as it is local to the shell session. Simply setting it will work as you'd want and won't pollute the environment for subshells and scripts.

And zsh users get another advantage here. You can use assign to the cdpath array or the CDPATH colon-delimited string, they are both treated the same internally. The advantage is being able to `cdpath+=...`, much like adding to $PATH with `path+=` or removing from PATH with `path^=`. Check zshbuiltins(1) for how to make your variables work like this, or how to use typeset -U to remove duplicates automatically, or $thousand_other_cool_things.

Note that CDPATH can break shell scripts that assume `cd` hasn't been adulterated.

A huge block of "unalias" calls at the beginning of shell scripts used to be a common practice, but they don't seem to be found in more widely-used tools these days.

Except with CDPATH the `cd` is usually not an alias. Even `/usr/bin/cd` is aware of CDPATH.

It's a bug in the script, just like reacting badly to $IFS or $LANG.

What is /usr/bin/cd for? cd is supposed to be a shell built-in, because running /usr/bin/cd will make another process and that cannot change the current working directory of the shell you are in.

EDIT:

  $ cat /usr/bin/cd
  #!/usr/bin/sh
  builtin cd "$@"

Look, it's 'cperciva!

  $ cat /usr/bin/cd
  #!/bin/sh
  # $FreeBSD: src/usr.bin/alias/generic.sh,v 1.2 2005/10/24 22:32:19 cperciva Exp $
  # This file is in the public domain.
  builtin `echo ${0##*/} | tr \[:upper:] \[:lower:]` ${1+"$@"}

TIL, magnificient! It doesn't work on the minimal Centos 7, so you need:

    yum install -y bash-completion
    bash      # a fresh run