Otdfbt

I am trying to create the postgresql database.

When I install PostgreSQL, I gave this command:

sudo yum install postgresql postgresql-server

and later I modified the config file:

sudo vim /var/lib/pgsql/data/pg_hba.conf

and modified as

local all all trust
host all all 127.0.0.1/32 trust
host all all ::1/128 trust
host all all 0.0.0.0/0 md5

While I am trying to startup the postgresql service:

sudo service postgresql initdb

> Data directory is not empty! [FAILED]

sudo chkconfig postgresql on

sudo service postgresql start

Starting postgresql service: [ OK ]

What is caused these errors and how do I fix them?

Initdb should only be run once. It will create the directory where you'll keep the config files and (usually) the actual database. You've obviously already done that already; otherwrise there wouldn't be any pg_hba.conf for you to edit.

So, just don't run postgresql initdb again, unless you are doing a complete reinstall.

From here:

If you're completely wiping & reinstalling a Postgres DB, when running initdb like:

service postgresql-9.2 initdb -E 'UTF8' --pgdata="/foo/bar/"

you can encounter this service error:

Data directory is not empty! [FAILED]

To fix it (and this is the nuclear option -- all db data is wiped!)

On Amazon Linux (2014-x):

rm -rf /var/lib/pgsql9/data

On CentOS (6.x)

rm -rf /var/lib/pgsql/9.2/data

Now try the initdb command again and it should work this time:

service postgresql-9.2 initdb

On systemd based systems like RHEL/CentOS 7 and Fedora the procedure for running initdb is somewhat different. This is no longer done by the init scripts (which no longer exist), and the new procedure is much closer to the upstream instructions.

You must first su to the postgres user, and then run initdb or pg_ctl initdb. It's not necessary to provide a data directory if you are using a Red Hat build as its default automatically chooses the default data directory /var/lib/pgsql.

For example:

# su - postgres
$ pg_ctl initdb
$ exit
#

Of course, you only do this once, on first installation, to set up the initial data directory. You would not do it again unless you were creating a completely new installation or restoring from a disaster.

I had the same issue, using PostgreSQL 9.3 on CentOS 6.

I deleted the /var/lib/pgsql/9.3/data folder, then re-ran the command

sudo service postgresql-9.3 initdb

... which successfully initialised the db service again.