mac upgrade postgres to 9.4.0 after automatic homebrew upgrade

pg.sh

newpg=9.4.0
oldpg=9.3.5_1 # set this to your current PG version

# Stop current Postgres server
# launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

# Backup current db
mv /usr/local/var/postgres/ /usr/local/var/postgres-$oldpg

# Homebrew
# Check here if you have issues with either of these https://github.com/Homebrew/homebrew/wiki#troubleshooting
# brew update
# brew upgrade postgresql

# OS X launch agents for PG, so it starts on boot automatically
# cp /usr/local/Cellar/postgresql/$newpg/homebrew.mxcl.postgresql.plist ~/Library/LaunchAgents/

# These settings may or may not be necessary, investigate on your own
# http://www.postgresql.org/docs/9.3/static/kernel-resources.html
# sudo sysctl -w kern.sysv.shmall=65536
# sudo sysctl -w kern.sysv.shmmax=16777216

# Create new DB
initdb /usr/local/var/postgres

# Upgrade old DB to new DB
mkdir -p /tmp/pgupgrade && cd $_
pg_upgrade -d /usr/local/var/postgres-$oldpg/ \
  -D /usr/local/var/postgres \
  -b /usr/local/Cellar/postgresql/$oldpg/bin \
  -B /usr/local/Cellar/postgresql/$newpg/bin

# Start new Postgres server
# launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

echo "Check if it works and delete /usr/local/var/postgres-$oldpg"

this is a simplified fork of a script by cjolly: https://gist.github.com/cjolly/2870054
my postgresql was already upgraded. i just needed to be able to use it, so I commented out all the unnecessary steps