$ brew update
Error: Permission denied - /usr/local/Library/Formula/abyss-explorer.rb
$ brew upgrade
==> Upgrading 20 outdated packages, with result:
ant 1.9.4, automake 1.14.1, elasticsearch 1.2.0, erlang R16B03-1, gd 2.1.0_2, git 1.9.3, gnuplot 4.6.5, ios-sim 1.9.0, leiningen 2.3.4, libgpg-error 1.13, libpng 1.6.10, libyaml 0.1.6, maven 3.2.1, mongodb 2.6.1, openssl 1.0.1g, python 2.7.6_1, readline 6.3.5, redis 2.8.9, sqlite 3.8.4.3, wget 1.15_1
==> Upgrading ant
==> Downloading https://downloads.sf.net/project/machomebrew/Bottles/ant-1.9.4.mavericks.bottle.tar.gz
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==> Pouring ant-1.9.4.mavericks.bottle.tar.gz