Can't find the 'libpq-fe.h header when trying to install pg gem

Question

I am using the Ruby on Rails 3.1 pre version. I like to use PostgreSQL, but the problem is installing the pg gem. It gives me the following error:

$ gem install pg Building native extensions.  This could take a while... ERROR:  Error installing pg:     ERROR: Failed to build gem native extension.          /home/u/.rvm/rubies/ruby-1.9.2-p0/bin/ruby extconf.rb checking for pg_config... no No pg_config... trying anyway. If building fails, please try again with  --with-pg-config=/path/to/pg_config 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/u/.rvm/rubies/ruby-1.9.2-p0/bin/ruby     --with-pg     --without-pg     --with-pg-dir     --without-pg-dir     --with-pg-include     --without-pg-include=${pg-dir}/include     --with-pg-lib     --without-pg-lib=${pg-dir}/lib     --with-pg-config     --without-pg-config     --with-pg_config     --without-pg_config   Gem files will remain installed in /home/u/.rvm/gems/ruby-1.9.2-p0/gems/pg-0.11.0 for inspection. Results logged to /home/u/.rvm/gems/ruby-1.9.2-p0/gems/pg-0.11.0/ext/gem_make.out 

How do I solve this problem?

Answer 1

It looks like in Ubuntu that header is part of the libpq-dev package (at least in the following Ubuntu versions: 11.04 (Natty Narwhal), 10.04 (Lucid Lynx), 11.10 (Oneiric Ocelot), 12.04 (Precise Pangolin), 14.04 (Trusty Tahr) and 18.04 (Bionic Beaver)):

... /usr/include/postgresql/libpq-fe.h ... 

So try installing libpq-dev or its equivalent for your OS:

• For Ubuntu/Debian systems: sudo apt-get install libpq-dev
• On Red Hat Linux (RHEL) systems: yum install postgresql-devel
• For Mac Homebrew: brew install postgresql
• For Mac MacPorts PostgreSQL: gem install pg -- --with-pg-config=/opt/local/lib/postgresql[version number]/bin/pg_config
• For OpenSuse: zypper in postgresql-devel
• For ArchLinux: pacman -S postgresql-libs