Why won't PostgreSQL 9.3 start on Ubuntu?
My locale settings were not properly configured when PostgreSQL was installed. Purging and reinstalling didn't help. I followed the instructions here and that did the trick for me.



Essential parts of the linked information reproduced below:

The problem showed itself in the following manner:

warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
...
are supported and installed on your system.


The first one was very easy to solve by executing:

#dpkg-reconfigure locales


...and choosing the preferred locales.

But after that PostgreSQL still refused to start. This is due to the fact that the installation process tried to create a cluster at installation time but because of the bad locales this wasn't done. So we have to redo this step by executing: 

#pg_createcluster 9.3 main --start


(For the 9.3 version of PostgreSQL)

After that step PostgreSQL starts flawlessly via

#/etc/init.d/postgresql start