title: How to install pg gem in rails
body: <p>I tried to install pg gem. But it produce the following error. Can anyone help me to solve this problem ?</p>
  
  <pre><code>root@localhost:/home/rails/Project# gem install pg
  Building native extensions.  This could take a while...
  ERROR:  Error installing pg:
      ERROR: Failed to build gem native extension.
  
      current directory: /var/lib/gems/2.3.0/gems/pg-0.18.4/ext
  /usr/bin/ruby2.3 -r ./siteconf20160908-9582-xu3pmx.rb extconf.rb
  checking for pg_config... yes
  Using config values from /usr/bin/pg_config
  You need to install postgresql-server-dev-X.Y for building a server-side extension or libpq-dev for building a client-side application.
  You need to install postgresql-server-dev-X.Y for building a server-side extension or libpq-dev for building a client-side application.
  checking for libpq-fe.h... no
  Can't find the 'libpq-fe.h header
  *** extconf.rb failed ***
  Could not create Makefile due to some reason, probably lack of necessary
  libraries and/or headers.  Check the mkmf.log file for more details.  You may
  need configuration options.
  
  Provided configuration options:
      --with-opt-dir
      --without-opt-dir
      --with-opt-include
      --without-opt-include=${opt-dir}/include
      --with-opt-lib
      --without-opt-lib=${opt-dir}/lib
      --with-make-prog
      --without-make-prog
      --srcdir=.
      --curdir
      --ruby=/usr/bin/$(RUBY_BASE_NAME)2.3
      --with-pg
      --without-pg
      --enable-windows-cross
      --disable-windows-cross
      --with-pg-config
      --without-pg-config
      --with-pg_config
      --without-pg_config
      --with-pg-dir
      --without-pg-dir
      --with-pg-include
      --without-pg-include=${pg-dir}/include
      --with-pg-lib
      --without-pg-lib=${pg-dir}/lib
  
  To see why this extension failed to compile, please check the mkmf.log which can be found here:
  
    /var/lib/gems/2.3.0/extensions/x86-linux/2.3.0/pg-0.18.4/mkmf.log
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /var/lib/gems/2.3.0/gems/pg-0.18.4 for inspection.
  Results logged to /var/lib/gems/2.3.0/extensions/x86-linux/2.3.0/pg-0.18.4/gem_make.out
  root@localhost:/home/rails/Project# 
  </code></pre>