How do I add a directory to PATH when using `zsh` in Sierra
export

To change the path within your shell session, not system-wide, you can use the bash-style export command with zsh, as documented here. 

The name of the PATH variable is case-sensitive and must be all-uppercase.

export PATH=$PATH:/folder/you/want


To verify your change, run:

echo $PATH


You will see results like this.


  /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/folder/you/want