Installing the PostgreSQL gem with 'gem pq'

Question

I am learning Ruby on Rails and trying to develop an application. In my application I am trying to use the default SQLite database in the Development Mode and PostgreSQL in the Production Mode. But I'm getting the following error while trying to install pg gem using: gem install pg

Building native extensions.  This could take a while...
ERROR:  Error installing pg:
        ERROR: Failed to build gem native extension.
 
    /home/tusharkhatiwada/.rvm/rubies/ruby-2.0.0-p247/bin/ruby 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=/home/tusharkhatiwada/.rvm/rubies/ruby-2.0.0-p247/bin/ruby
        --with-pg
        --without-pg
        --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}/
 
 
Gem files will remain installed in /home/tusharkhatiwada/.rvm/gems/ruby-2.0.0-p247@rails4.0.0/g
ems/pg-0.17.0 for inspection.
Results logged to /home/tusharkhatiwada/.rvm/gems/ruby-2.0.0-p247@rails4.0.0/gems/pg-0.17.0/ext
/gem_make.out

After that I again tried with gem install pg -- --with-pg-config= '/usr/bin/pg_config' and the following error is displayed:

Building native extensions with: '--with-pg-config= /usr/bin/pg_config'
This could take a while...
ERROR:  Error installing pg:
        ERROR: Failed to build gem native extension.
 
    /home/tusharkhatiwada/.rvm/rubies/ruby-2.0.0-p247/bin/ruby extconf.rb --with-pg-config= /us
r/bin/pg_config
Using config values from 
sh: 1: : Permission denied
sh: 1: : Permission denied
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=/home/tusharkhatiwada/.rvm/rubies/ruby-2.0.0-p247/bin/ruby
        --with-pg
        --without-pg
        --with-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}/
 
 
Gem files will remain installed in /home/tusharkhatiwada/.rvm/gems/ruby-2.0.0-p247@rails4.0.0/g
ems/pg-0.17.0 for inspection.
Results logged to /home/tusharkhatiwada/.rvm/gems/ruby-2.0.0-p247@rails4.0.0/gems/pg-0.17.0/ext
/gem_make.out

Answer 1

You have to do this

sudo apt-get install libgmp-dev libpq-dev

and then

gem install pg

Answer 2

for those who reached this by google search if libpq-dev didnt work or threw another errors i hade the same problem try upgrading your system and get the ruby div-kit

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install ruby1.9.1-dev

then reboot after this just try again

...

Answer 3

If you are using Ubuntu try to install following lib file

sudo apt-get install libpq-dev

and then gem install pg

worked for me.