After configuring remote access,server can't be started

My postgresql 9.4 is installed in centos 6.7,and I have followed this:

http://www.cyberciti.biz/faq/postgresql-remote-access-or-connection/

1,cd /var/libpgsql/9.4/data

2,cp postgresql.conf.sample postgresql.conf

3,sudo vi postgresql.conf and add two lines,and save it:

> *listen_addresses = "*"tcpip_socket = true*

4,cp pg_hba.conf.sample pg_hba.conf

5,sudo vi pg_hba.conf then *commented(maybe this is uneccessary)*

> #host all all 127.0.0.1/32
> @authmethodhost@
> #host all all ::1/128
> @authmethodhost@

6,add two lines:(I have tried to change *md5 to trust*,neither works)

>
> *host all all 0.0.0.0/0 <http://0.0.0.0/0>
> md5host all all ::0/0
> md5*

7,then *save*:pg_hba.conf

8,then *restart* postgresql sever by

* sudo service postgresql-9.4 restart*

9.*close iptables*

* sudo service iptables stop*

*got error:*

> Stopping postgresql-9.4 service: [ OK ]
> Starting postgresql-9.4 service: * [FAILED]*

*tail /var/lib/pgsql/9.4/pgstartup.log,got*

> < 2015-11-22 11:47:42.691 CST >LOG: could not create IPv6 socket: Address
> family not supported by protocol
> < 2015-11-22 11:47:42.718 CST >LOG: redirecting log output to logging
> collector process
> < 2015-11-22 11:47:42.718 CST >HINT: Future log output will appear in
> directory "pg_log".

Questions are:
1, Is this "could not create IPv6..." just a warning or the actual reason
of starting failure?
2, Where is the pg_log directory?