Can't bundle Postgresql - ruby-on-rails

Question

When trying to run bundle install I get the following error
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
current directory: /Users/seque1990/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/pg-0.18.4/ext
/Users/seque1990/.rbenv/versions/2.2.2/bin/ruby -r ./siteconf20160117-46131-1dmnnnq.rb extconf.rb --with-pg-config=/opt/local/lib/postgresql91/bin/pg_config
Using config values from /opt/local/lib/postgresql91/bin/pg_config
sh: /opt/local/lib/postgresql91/bin/pg_config: No such file or directory
sh: /opt/local/lib/postgresql91/bin/pg_config: No such file or directory
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=/Users/seque1990/.rbenv/versions/2.2.2/bin/$(RUBY_BASE_NAME)
--with-pg
--without-pg
--enable-windows-cross
--disable-windows-cross
--with-pg-config
--with-pg-dir
--without-pg-dir
--with-pg-include
--without-pg-include=${pg-dir}/include
--with-pg-lib
--without-pg-lib=${pg-dir}/lib
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/Users/seque1990/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/extensions/x86_64-darwin-15/2.2.0-static/pg-0.18.4/mkmf.log
extconf failed, exit code 1
Gem files will remain installed in /Users/seque1990/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/pg-0.18.4 for inspection.
Results logged to /Users/seque1990/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/extensions/x86_64-darwin-15/2.2.0-static/pg-0.18.4/gem_make.out
After getting that I did brew install postgresql but it tells me that it is already installed but not linked.
Then I tried brew link postgresql but it tells me:
Error: Could not symlink share/man/man3/SPI_connect.3
/usr/local/share/man/man3 is not writable.
Not sure how to proceed. :(

Answer 1

If your using ubuntu machine then,
sudo apt-get install postgresql
sudo apt-get install libpq-dev
And Then,gem install pg
For oSx, you need to specify the pg_config path
gem install pg -- --with-pg-config=`which pg_config`
which pg_config gives you the file path where it is installed.