$brew doctor

Warning: Homebrew's sbin was not found in your PATH but you have installed
formulae that put executables in /usr/local/sbin.
Consider setting the PATH for example like so
    echo export PATH='/usr/local/sbin:$PATH' >> ~/.bash_profile

add export PATH="/usr/local/sbin:$PATH" to ~/.bash_profile 
or run echo export PATH='/usr/local/sbin:$PATH' >> ~/.bash_profile