function zsh_clear_env () {
  for V in `set +`; do case "$V" in
    '!'|'$'|'*'|'@'|'?'|'-'|'#'|[0-9]|V);;
    **) typeset +r "$V"; unset "$V";;
  esac; done
  unset V
  emulate zsh
  export IFS=" \t\n"
  export PATH="/bin:/usr/bin:/sbin:/usr/sbin"
}
