##  Homebrew  ##########################


  * update error because of git

    error message
  +---------------------------------------------------------------------------------+
  | error: Your local changes to the following files would be overwritten by merge: |
  | ...                                                                             |
  | Please, commit your changes or stash them before you can merge.                 |
  |                                                                                 |
  | Aborting                                                                        |
  | Error: Failure while executing: git pull -q origin ....                         |
  +---------------------------------------------------------------------------------+

    reset /usr/local
  +----------------------------------+
  | $ cd $(brew --prefix)            |
  | $ git fetch origin               |
  | $ git reset --hard origin/master |
  +----------------------------------+


  * permission error

    update failure because of "Permission denied"
  +-----------------------------------+
  | $  sudo chown -R $USER /usr/local |
  +-----------------------------------+