Unable to install pg gem file on CENT OS

PavanKumar Chamarthi wrote in post #1087845:

please help me in this... I am unable to install pg gem file

[root@vdimc04 ~]# gem install pg -v '0.12.0'
/usr/local/lib/ruby/1.9.1/yaml.rb:56:in `<top (required)>':
It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your
Fetching: rake-compiler-0.8.1.gem (100%)
Fetching: pg-0.12.0.gem (100%)
Building native extensions. This could take a while...
ERROR: Error installing pg:
    ERROR: Failed to build gem native extension.

        /usr/local/bin/ruby extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with

checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***

It is in your own interest to provide more detail respecting your
installation when reporting a problem and asking for help. For example,
are you running CentOS-6 or 5? What point release? Are you using the
stock PostgreSQl install, have you installed a different version from
another respoitory, or have you built PostgreSQl yourself? In any case
what version of Postgres?

Providing that you are running CentOS-6.x; and assuming that you are
evidently not using the Postgres provided with that distribution; and
guessing that you are likely using the pgdg-91-centos.repo; and also
guessing that you are using either rvm or rbenv then you likely need to
do something akin to the following

yum install postgresql91-devel libyaml
gem install pg --with-pg-config=/usr/pgsql-9.1/bin/pg_config