I'm trying to install the pg gem in order to work again with my rails projects. But I get this error:

Building native extensions. This could take a while… ERROR: Error
installing pg: ERROR: Failed to build gem native extension.

/Users/jeanosorio/.rvm/rubies/ruby-2.0.0-p247/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=/Users/jeanosorio/.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
/Users/jeanosorio/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/gems/2.0.0/gems/pg-0.17.0
for inspection. Results logged to
/Users/jeanosorio/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/gems/2.0.0/gems/pg-0.17.0/ext/gem_make.out

I tried everything I found on stackoverflow but I still get this error.

If I try to install postgresql using brew I get the following waring:

Warning: postgresql-9.2.4 already installed, it's just not linked

If I try to link

brew link postgresql Linking /usr/local/Cellar/postgresql/9.2.4…
Warning: Could not link postgresql. Unlinking…

Error: Could not symlink file:
/usr/local/Cellar/postgresql/9.2.4/share/man/man7/WITH.7
/usr/local/share/man/man7 is not writable. You should change its
permissions.

Help Please

NOTE: I already installed the command line tools for mavericks.

If I uninstall using homebrew and try to install again, I get this error:

==> Downloading http://ftp.postgresql.org/pub/source/v9.2.4/postgresql-9.2.4.tar.bz2

################################################################## 100.0%

==> Patching patching file src/pl/plpython/Makefile patching file contrib/uuid-ossp/uuid-ossp.c
==> ./configure –prefix=/usr/local/Cellar/postgresql/9.2.4 –datadir=/usr/local/Cellar/postgresql/9.2.4/share/postgresql –docdir=/usr/local/Cellar/p
==> make install-world
==> Caveats

Build Notes

If builds of PostgreSQL 9 are failing and you have version 8.x
installed, you may need to remove the previous version first. See:
https://github.com/mxcl/homebrew/issues/issue/2510

Create/Upgrade a Database

If this is your first install, create a database with: initdb
/usr/local/var/postgres -E utf8

To migrate existing data from a previous major version (pre-9.2) of
PostgreSQL, see:
http://www.postgresql.org/docs/9.2/static/upgrading.html

Loading Extensions

By default, Homebrew builds all available Contrib extensions. To see a
list of all available extensions, from the psql command line, run:
SELECT * FROM pg_available_extensions;

To load any of the extension names, navigate to the desired database
and run: CREATE EXTENSION [extension name];

For instance, to load the tablefunc extension in the current database,
run: CREATE EXTENSION tablefunc;

For more information on the CREATE EXTENSION command, see:
http://www.postgresql.org/docs/9.2/static/sql-createextension.html For
more information on extensions, see:
http://www.postgresql.org/docs/9.2/static/contrib.html

Other

Some machines may require provisioning of shared memory:
http://www.postgresql.org/docs/9.2/static/kernel-resources.html#SYSVIPC
When installing the postgres gem, including ARCHFLAGS is recommended:
ARCHFLAGS="-arch x86_64" gem install pg

To install gems without sudo, see the Homebrew wiki.

To have launchd start postgresql at login:
ln -sfv /usr/local/opt/postgresql/*.plist ~/Library/LaunchAgents Then to load postgresql now:
launchctl load ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist Or, if you don't
want/need launchctl, you can just run:
pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start Warning: Could not link
postgresql. Unlinking… Error: The brew link step did not complete
successfully The formula built, but is not symlinked into /usr/local
You can try again using `brew link postgresql'
==> Summary 🍺 /usr/local/Cellar/postgresql/9.2.4: 2831 files, 38M, built in 4.9 minutes

SOLUTION:

I execute this command in order to change the permission of the folder:

sudo chown jeanosorio /usr/local/share/man/man7

Then

brew link postgresql Linking /usr/local/Cellar/postgresql/9.3.1… 421
symlinks created

And finally:

sudo ARCHFLAGS="-arch x86_64" gem install pg

Fetching: pg-0.17.0.gem (100%) Building native extensions. This could
take a while… Successfully installed pg-0.17.0