Homebrew postgres broken

I had the same problem installing postgres using homebrew on a freshly installed Yosemite.

First off my brew config looks like this:

HOMEBREW_VERSION: 0.9.5
ORIGIN: https://github.com/Homebrew/homebrew
HEAD: 9f6926265f8e4be7cc80dfe9042f2cd3c1e8dc9e
Last commit: 64 minutes ago
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CELLAR: /usr/local/Cellar
CPU: quad-core 64-bit sandybridge
OS X: 10.10.1-x86_64
Xcode: 6.1.1
Clang: 6.0 build 600
X11: N/A
System Ruby: 2.0.0-481
Perl: /usr/bin/perl
Python: /usr/bin/python
Ruby: ~/.rvm/rubies/ruby-2.1.1/bin/ruby

First thing i noticed was that I had no write permission to /usr/local/var/postgres. This was easily changed issuing sudo chown -R `whoami` /usr/local/var/postgres then I reinstalled postgresql and did

cat /usr/local/var/postgres/server.log

which revealed:

postgres cannot access the server configuration file "/usr/local/var/postgres/postgresql.conf": No such file or directory

So I removed the directory /usr/local/var/postgres and issued the command to initialize the database.

initdb -D /usr/local/var/postgres/

This seemed to have done the trick and postgres is running fine.

I had this same problem. The primary issue here is that the initdb step of installation will create the directory with root ownership instead of as the user on a Mac. To solve this issue:

Create the data directory before running initdb and set permissions of 0700

rm -rf /usr/local/var/postgres  # in case this is not your first try
mkdir /usr/local/var/postgres
chmod 0700 /usr/local/var/postgres

Then run initdb and it will respect the permissions of the data directory.

initdb -D /usr/local/var/postgres

For grins and giggles, create a test db named after your user:

createdb `whoami`

Login to test:

psql

After trying to install postgresql with Homebrew, I got this:

Warning: postgresql-9.5.2 already installed, it's just not linked

So I tried:

brew link postgresql

And got this error:

Linking /usr/local/Cellar/postgresql/9.5.2... 
Error: Could not symlink share/man/man3/SPI_connect.3
/usr/local/share/man/man3 is not writable.

It seemed to be a write permission matter, so I did:

sudo chown -R `whoami` /usr/local/share/man/

It did the trick because, then I was able to do (without error):

brew link postgresql