# Pastebin tcDaEnB1
$ brew install rbenv ruby-build
Error: The following directories are not writable by your user:
/usr/local/Cellar
/usr/local/Frameworks
/usr/local/Homebrew
/usr/local/bin
/usr/local/etc
/usr/local/etc/bash_completion.d
/usr/local/include
/usr/local/lib
/usr/local/lib/pkgconfig
/usr/local/lib/python3.7/site-packages
/usr/local/opt
/usr/local/sbin
/usr/local/share
/usr/local/share/aclocal
/usr/local/share/doc
/usr/local/share/info
/usr/local/share/locale
/usr/local/share/man
/usr/local/share/man/man1
/usr/local/share/man/man3
/usr/local/share/man/man5
/usr/local/share/man/man6
/usr/local/share/man/man7
/usr/local/share/man/man8
/usr/local/share/zsh
/usr/local/share/zsh/site-functions
/usr/local/var/homebrew/linked
/usr/local/var/homebrew/locks
/usr/local/var/log

You should change the ownership of these directories to your user.
  sudo chown -R $(whoami) /usr/local/Cellar /usr/local/Frameworks /usr/local/Homebrew /usr/local/bin /usr/local/etc /usr/local/etc/bash_completion.d /usr/local/include /usr/local/lib /usr/local/lib/pkgconfig /usr/local/lib/python3.7/site-packages /usr/local/opt /usr/local/sbin /usr/local/share /usr/local/share/aclocal /usr/local/share/doc /usr/local/share/info /usr/local/share/locale /usr/local/share/man /usr/local/share/man/man1 /usr/local/share/man/man3 /usr/local/share/man/man5 /usr/local/share/man/man6 /usr/local/share/man/man7 /usr/local/share/man/man8 /usr/local/share/zsh /usr/local/share/zsh/site-functions /usr/local/var/homebrew/linked /usr/local/var/homebrew/locks /usr/local/var/log

And make sure that your user has write permission.
  chmod u+w /usr/local/Cellar /usr/local/Frameworks /usr/local/Homebrew /usr/local/bin /usr/local/etc /usr/local/etc/bash_completion.d /usr/local/include /usr/local/lib /usr/local/lib/pkgconfig /usr/local/lib/python3.7/site-packages /usr/local/opt /usr/local/sbin /usr/local/share /usr/local/share/aclocal /usr/local/share/doc /usr/local/share/info /usr/local/share/locale /usr/local/share/man /usr/local/share/man/man1 /usr/local/share/man/man3 /usr/local/share/man/man5 /usr/local/share/man/man6 /usr/local/share/man/man7 /usr/local/share/man/man8 /usr/local/share/zsh /usr/local/share/zsh/site-functions /usr/local/var/homebrew/linked /usr/local/var/homebrew/locks /usr/local/var/log